THE M240G MACHINEGUNNER. Maintenance Manual MCI 0321B (2007)

Student Information

Number and

MCI 0321B

Title

THE M240G MACHINEGUNNER

Study Hours

Course

Text

Material

Review Agency School of Infantry (East)

Reserve

Retirement

Credits (RRC)

ACE

Not applicable to civilian training/education.

Assistance

For administrative assistance, have your training officer or NCO log on to the

MCI home page at www.mci.usmc.mil. Marines CONUS may call toll free

1-800-MCI-USMC. Marines worldwide may call commercial (202) 685-

7596 or DSN 325-7596.

MCI Course 0321B

iii

Study Guide

Congratulations

Congratulations on your enrollment in a distance education course from the

Distance Learning and Technologies Department (DLTD) of the Marine

Corps Institute (MCI). Since 1920, the Marine Corps Institute has been

helping tens of thousands of hard-charging Marines, like you, improve their

technical job performance skills through distance learning. By enrolling in

this course, you have shown a desire to improve the skills you have and

master new skills to enhance your job performance. The distance learning

course you have chosen, MCI 0321B, The M240G Machinegunner, provides

instruction to all Marines tasked with operating the M240G medium

machinegun. This course consists of learning experiences necessary to

perform those duties associated with operating and maintaining the M240G

and all of its associated equipment.

Your Personal

•

YOU ARE PROPERLY MOTIVATED. You have made a positive

Characteristics

decision to get training on your own. Self-motivation is perhaps the most

important force in learning or achieving anything. Doing whatever is

necessary to learn is motivation. You have it!

•

YOU SEEK TO IMPROVE YOURSELF. You are enrolled to improve

those skills you already possess, and to learn new skills. When you

improve yourself, you improve the Corps!

•

YOU HAVE THE INITIATIVE TO ACT. By acting on your own, you

have shown you are a self-starter, willing to reach out for opportunities to

learn and grow.

•

YOU ACCEPT CHALLENGES. You have self-confidence and believe

in your ability to acquire knowledge and skills. You have the self-

confidence to set goals and the ability to achieve them, enabling you to

meet every challenge.

•

YOU ARE ABLE TO SET AND ACCOMPLISH PRACTICAL

GOALS. You are willing to commit time, effort, and the resources

necessary to set and accomplish your goals. These professional traits will

help you successfully complete this distance learning course.

Continued on next page

MCI Course 0321B

Study Guide, Continued

Beginning Your Before you actually begin this course of study, read the student information

Course

page. If you find any course materials missing, notify your training officer or

training NCO. If you have all the required materials, you are ready to begin.

To begin your course of study, familiarize yourself with the structure of the

course text. One way to do this is to read the table of contents. Notice the

table of contents covers specific areas of study and the order in which they are

presented. You will find the text divided into several study units. Each study

unit is comprised of two or more lessons and lesson exercises.

Leafing

Leaf through the text and look at the course. Read a few lesson exercise

Through the

questions to get an idea of the type of material in the course. If the course has

Text

additional study aids, such as a handbook or plotting board, familiarize

yourself with them.

The First Study Turn to the first page of study unit 1. On this page, you will find an

Unit

introduction to the study unit and generally the first study unit lesson. Study

unit lessons contain learning objectives, lesson text, and exercises.

Reading the

Learning objectives describe in concise terms what the successful learner,

Learning

you, will be able to do as a result of mastering the content of the lesson text.

Objectives

Read the objectives for each lesson and then read the lesson text. As you read

the lesson text, make notes on the points you feel are important.

Completing the To determine your mastery of the learning objectives and text, complete the

Exercises

exercises developed for you. Exercises are located at the end of each lesson,

and at the end of each study unit. Without referring to the text, complete the

exercise questions and then check your responses against those provided.

Continued on next page

MCI Course 0321B

Study Guide, Continued

Continuing to

Continue on to the next lesson, repeating the above process until you have

March

completed all lessons in the study unit. Follow the same procedures for each

study unit in the course.

Preparing for

To prepare for your final exam, you must review what you learned in the

the Final Exam

course. The following suggestions will help make the review interesting and

challenging.

•

CHALLENGE YOURSELF. Try to recall the entire learning sequence

without referring to the text. Can you do it? Now look back at the text to

see if you have left anything out. This review should be interesting.

Undoubtedly, you’ll find you were not able to recall everything. But with

a little effort, you’ll be able to recall a great deal of the information.

•

USE UNUSED MINUTES. Use your spare moments to review. Read

your notes or a part of a study unit, rework exercise items, review again;

you can do many of these things during the unused minutes of every day.

•

APPLY WHAT YOU HAVE LEARNED. It is always best to use the

skill or knowledge you’ve learned as soon as possible. If it isn’t possible

to actually use the skill or knowledge, at least try to imagine a situation in

which you would apply this learning. For example make up and solve

your own problems. Or, better still, make up and solve problems that use

most of the elements of a study unit.

•

USE THE “SHAKEDOWN CRUISE” TECHNIQUE. Ask another

Marine to lend a hand by asking you questions about the course. Choose a

particular study unit and let your buddy “fire away.” This technique can

be interesting and challenging for both of you!

•

MAKE REVIEWS FUN AND BENEFICIAL. Reviews are good habits

that enhance learning. They don’t have to be long and tedious. In fact,

some learners find short reviews conducted more often prove more

beneficial.

Continued on next page

MCI Course 0321B

vii

Study Guide, Continued

Tackling the

When you have completed your study of the course material and are confident

Final Exam

with the results attained on your study unit exercises, take the sealed envelope

marked “FINAL EXAM” to your unit training NCO or training officer.

Your training NCO or officer will administer the final examination and return

the examination and the answer sheet to MCI for grading. Before taking your

final examination, read the directions on the DP-37 answer sheet carefully.

Completing

The sooner you complete your course, the sooner you can better yourself by

Your Course

applying what you’ve learned! However, you do have 2 years from the date

of enrollment to complete this course.

Graduating!

As a graduate of this distance education course and as a dedicated Marine,

your job performance skills will improve, benefiting you, your unit, and the

Marine Corps.

Semper Fidelis!

MCI Course 0321B

viii

STUDY UNIT 1

INTRODUCTION TO THE M240G MEDIUM MACHINEGUN

Overview

Scope

The successful use and employment of the M240G medium machinegun

requires a basic knowledge of the weapon. To properly use and maintain the

M240G medium machinegun, you must know the weapon from one end to

the other—the parts, how it works, what it is capable of, and what it shoots.

In this study unit, you will learn the characteristics, nomenclature, and

functioning of the M240G medium machinegun. You will also learn the steps

for clearing, disassembling, assembling, and performing a function check.

The different types of ammunition used with the M240G and how the

ammunition is handled and stored will also be covered.

In This Study

This study unit contains the following lessons:

Unit

Lesson

See Page

Characteristics, Nomenclature, and Functioning

1-3

Clearing, Disassembly, Assembly, and Function Check

1-29

Ammunition

1-53

MCI Course 0321B

1-1

Study Unit 1

LESSON 1

CHARACTERISTICS, NOMENCLATURE, AND FUNCTIONING

Introduction

Scope

Knowing the capabilities of a weapon is essential to its use. However, to

maintain it, you must know what all the parts are and how they go together.

In this lesson, you will learn the purpose of the M240G medium machinegun;

the characteristics, capabilities, and nomenclature; and the nomenclature and

purpose of the related SL-3 components. Also, you will learn the steps in the

cycle of operation for the M240G.

Learning

After completing this lesson, you should be able to

Objectives

• Identify the purpose of the M240G medium machinegun.

• Identify the characteristics of the M240G medium machinegun.

• Identify the capabilities of the M240G medium machinegun.

• Identify the nomenclature of the M240G medium machinegun.

• Identify the purpose for each assembly of the M240G medium

machinegun.

• Identify the nomenclature of the M240G medium machinegun SL-3

components.

• Identify the purpose of the M240G medium machinegun SL-3

components.

• Identify the steps in the cycle of operation of the M24G medium

machinegun.

Continued on next page

MCI Course 0321B

1-3

Study Unit 1, Lesson 1

Purpose of the M240G Medium Machinegun

Two-Fold

The M240G medium machinegun is used in offensive and defensive combat,

combat support, and combat logistics units in all parts of the MAGTF. The

purpose of the M240G is to

• Provide heavy volumes of close, accurate, and continuous fire support to

suppress and destroy enemy personnel in support of an attack.

• Serve as an integral part of a unit’s defensive fire plan when employing

final protective fires by breaking up and stopping an enemy’s assault.

MCI Course 0321B

1-5

Study Unit 1, Lesson 1

Characteristics and Capabilities

Descriptive

The M240G has four descriptive characteristics:

Characteristics

Characteristic

Description

Belt-fed

The gun is fed by a disintegrating metallic link belt.

Air-cooled

The barrel and receiver are exposed to permit cooling

by the air.

Gas-operated

Gas produced from firing one round provides the

energy to mechanically prepare the weapon to fire the

next.

Fully automatic

Continues to fire until the trigger is released, a

malfunction occurs, or the ammunition is exhausted.

Weight

The table below lists the weights of selected components of the M240G:

Item

Weight in Pounds

Machinegun (complete)

25.6

Spare barrel w/case (SL-3 complete)

6.6

M122 tripod, flex-mount, and traversing and

elevation (T&E) mechanism (complete)

Dimensions

The table below lists the dimensions of the M240G:

Item

Dimension in Inches

Length

Height on M122 tripod

Rifling

The barrels of the M240G consist of the following rifling characteristics:

• Four grooves

• Uniform right hand turn

• One turn per 12 inches

Continued on next page

MCI Course 0321B

1-6

Study Unit 1, Lesson 1

Characteristics and Capabilities, Continued

Rates of Fire

The table below lists the rates of fire for the M240G:

Rates

Rounds per Minute

Remarks

Fires continuously depending on the

Cyclic

650 to 950

gas setting

Fires 6 to 8 round bursts with 4 or 5

Sustained

100

seconds between bursts

Fires 10- to 12-round bursts with 2 or

Rapid

200

3 seconds between bursts

Range

The table below lists the ranges of the M240G:

Range

Limits in Meters

Maximum overall

3725

Maximum effective area target

1800

Maximum effective point target

800

Tracer burnout

About 900

Grazing fire

600

Limits of

The table below lists the traverse limits for the M240G (with M122 tripod and

Manipulation

T&E mechanism):

Item

Limits in Mils

Elevation

247

Depression

200

Traverse (traversing bar)

875

425 left/450 right

MCI Course 0321B

1-7

Study Unit 1, Lesson 1

Nomenclature

Main

The M240G medium machinegun consists of the following main components:

Components

Item

Component

Barrel group

Buttstock and buffer group

Drive spring rod assembly (operating group sub-assembly)

Bolt and operating rod assembly (operating group sub-assembly)

Trigger housing group

Cover assembly (receiver group sub-assembly)

Feed tray (receiver group sub-assembly)

Receiver assembly (receiver group sub-assembly)

Continued on next page

MCI Course 0321B

1-8

Study Unit 1, Lesson 1

Nomenclature, Continued

Barrel Group

The barrel group houses rounds for firing and directs the projectile after

firing. Components of the barrel group are shown in the graphic below:

Buttstock and

The buttstock and buffer assembly absorbs the recoil for the bolt and

Buffer Group

operating rod assembly at the end of the recoil movement. Components of

the buttstock and buffer assembly are shown in the graphic below:

Continued on next page

MCI Course 0321B

1-9

Study Unit 1, Lesson 1

Nomenclature, Continued

Drive Spring

The drive spring rod assembly is part of the operating group. It provides

Rod Assembly

energy for returning the bolt and operating rod assembly to the firing position.

Bolt and

The bolt and operating rod assembly is part of the operating group. It

Operating Rod

provides feeding, striping, chambering, firing, extraction, and ejection of

Assembly

cartridges using the projectile-propelling gases for power. Components of the

bolt and operating rod assembly are shown in the graphic below:

Continued on next page

MCI Course 0321B

1-10

Study Unit 1, Lesson 1

Nomenclature, Continued

Trigger

The trigger housing group controls the firing of the machinegun.

Housing Group

Components of the trigger housing group are shown in the graphic below:

Cover

The cover assembly is part of the receiver group. It feeds linked belt

Assembly

ammunition and positions and holds rounds in position for stripping, feeding,

and chambering. The cover has an integral sight mounting rail for current and

future accessories. Components of the cover assembly are shown in the

graphic below:

Continued on next page

MCI Course 0321B

1-11

Study Unit 1, Lesson 1

SL-3 Components, Continued

Gun Bag

The gun bag is used to carry and protect the M240G machinegun. It consists

of a large outer bag and a smaller, removable spare barrel bag inside. The

complete gun bag is used to carry the machinegun, tripod, flex-mount, spare

barrel, and all other SL-3 components. The removable spare barrel bag is

designed for field use and will carry the spare barrel and a complete set of

user maintenance equipment and accessories.

Combination

The combination scraper and extractor tool is used for removing carbon from

Scraper and

certain areas of the weapon during maintenance.

Extractor Tool

Front Sight

The front sight adjustment tool is used for adjusting the front sight of the

Adjustment

M240G during zeroing procedures.

Tool

Ruptured

The ruptured cartridge extractor is used to remove ruptured cartridges from

Cartridge

the chamber during troubleshooting procedures.

Extractor

Continued on next page

MCI Course 0321B

1-16

Study Unit 1, Lesson 1

SL-3 Components, Continued

Combination

The combination regulator scraper—also known as the scraper tool—is used

Regulator

to remove carbon buildup from the gas regulator plug during maintenance.

Scraper

Large and

The reamers are used to clean the gas port holes on the gas regulator plug and

Small Reamers

the barrel.

Cleaning Rod

The five sections and handle assembly of the cleaning rod join together to

with

make the cleaning rod. The attachments are used with the cleaning rod to

Attachments

assist in the cleaning of various parts of the M240G.

Continued on next page

MCI Course 0321B

1-17

Study Unit 1, Lesson 1

Functioning

Cycle of

The functioning of the M240G consists of a cycle of operation that can be

Operation

broken down into eight basic steps. Understanding how the M240G functions

will make it easier to recognize and correct malfunctions and stoppages that

occur during firing. The eight steps are listed below:

• Feeding

• Chambering

• Locking

• Firing

• Unlocking

• Extracting

• Ejecting

• Cocking

Feeding

Feeding is the process of moving the next round in the belt of ammunition

onto the feed tray groove. When the bolt is to the rear, the outer feed pawls

are outside the first round of ammunition. The inner feed pawl is between the

first and second rounds.

• The bolt moves forward to fire the round in the feed tray groove, causing

the belt feed pawl to move to the left.

• The feed pawl moves up and over the second round in the belt of

ammunition and is now in position to drag the second round into the feed

tray groove.

• The bolt moves to the rear after firing, causing the belt feed pawl to move

to the right, dragging the second round into the feed tray groove.

• Inside the cover, the cam roller, the feed arm with control spring, the feed

arm fork, and the pivot arm are present only so the feed pawls can move

back and forth, dragging rounds into position to be chambered.

Continued on next page

MCI Course 0321B

1-19

Study Unit 1, Lesson 1

Functioning, Continued

Chambering

Chambering is the process of stripping a round from the belt and seating it in

the chamber.

• The bolt travels forward, causing the upper locking lug of the bolt to

contact the base of the cartridge.

• The bolt strips the round from the belt link.

• The chambering ramp angles downward and forces the round toward the

chamber along with the spring tension of the cartridge guide pawl.

• The cartridge guide pawl also holds back the belt link.

• When the round is fully seated in the chamber, the extractor snaps over

the extractor rim of the cartridge, and the ejector is depressed.

Locking

Locking is the process of seating the bolt into the barrel socket. Although the

term locking is used here, it should be noted that in the M240G the bolt and

barrel do not physically interlock. This is why the barrel can be removed

even when the bolt is forward.

• During chambering, the bolt enters the barrel socket as the operating rod

is driven forward by the drive spring and the locking lever.

• Once the operating group with the bolt is all the way forward, the bolt is

“locked” into the barrel socket.

Firing

Firing is the process of detonating the round in the chamber.

• After the bolt reaches its locked position, the operating rod continues to

move forward, independent of the bolt.

• It carries the striker of the fixed firing pin through the aperture in the face

of the bolt, striking and detonating the primer of the cartridge.

Continued on next page

MCI Course 0321B

1-20

Study Unit 1, Lesson 1

Functioning, Continued

Unlocking

Unlocking is the process of moving the bolt back and out of the barrel socket.

• After the cartridge ignites and the projectile passes the gas port, part of the

gases enter the gas cylinder.

• The rapidly expanding gas enters the hollow end cap of the gas piston and

forces the operating group to the rear, providing the power for the last

four steps in the cycle of functioning.

• The operating rod now moves rearward, independent of the bolt, for a

short distance.

• The locking lever begins to swing toward the rear, carrying the bolt with it

into its unlocked position, and clears the barrel socket.

Extracting

Extracting is the process of removing the expended cartridge from the

chamber. The extractor grips the rim of the cartridge as the bolt and operating

rod pull the case from the chamber.

Continued on next page

MCI Course 0321B

1-21

Study Unit 1, Lesson 1

Functioning, Continued

Ejecting

Ejecting is the process of expelling the spent cartridge and link from the

weapon.

• The cartridge is withdrawn from the chamber, with the ejector exerting a

push from the top, and the extractor exerting a pull from the bottom.

• The casing falls from the gun as soon as it reaches the cartridge ejection

port.

• At approximately the same time, the empty link is forced out of the link

ejection port between the cartridge stops on the feed tray by the next

round moving into the feed tray groove.

Cocking

Cocking is the process of placing the parts of the gun in position to fire the

next round.

• During the rearward independent movement of the operating rod, the

firing pin striker is withdrawn from the face of the bolt.

• The bolt moves to the rear, far enough to pick up the next round for

chambering.

MCI Course 0321B

1-22

Study Unit 1, Lesson 1

Lesson 1 Exercise

Directions

Complete exercise items 1 through 8 by performing the action required.

Check your answers against those listed at the end of this lesson.

Item 1

Two purposes of the M240G medium machinegun are to

•

___________________________________________________________

•

___________________________________________________________

Item 2

The four descriptive characteristics of the M240G medium machinegun are

•

__________________________________________________________

•

__________________________________________________________

•

__________________________________________________________

•

__________________________________________________________

Item 3

Complete the following statement.

The maximum effective range of the M240G on an area target is __________

meters.

Continued on next page

MCI Course 0321B

1-23

Study Unit 1, Lesson 1 Exercise

Lesson 1 Exercise, Continued

Item 4

Identify the main assembly for each item (A through H) shown below:

___________________________________________________________

Item 5

The barrel assembly houses the round and _________________ the projectile

after firing.

a. aims

b. directs

c. removes

d. catches

Continued on next page

MCI Course 0321B

1-24

Study Unit 1, Lesson 1 Exercise

Lesson 1 Exercise, Continued

Item 6

Identify the SL-3 component shown below:

______________________________________________________________

Item 7

The purpose of the ruptured cartridge extractor is to remove a ruptured

cartridge from the

a. receiver.

b. buffer.

c. chamber.

d. feed tray.

Item 8

List the eights steps in the M240G cycle of operation.

•

__________________________________________________________

•

__________________________________________________________

•

__________________________________________________________

•

__________________________________________________________

•

__________________________________________________________

•

__________________________________________________________

•

__________________________________________________________

•

__________________________________________________________

Continued on next page

MCI Course 0321B

1-25

Study Unit 1, Lesson 1 Exercise

Lesson 1 Exercise, Continued

Answers

The table below lists the answers to the exercise items. If you have questions

about the items, refer to the reference page.

Item Number

Answer

Reference Page

• Provide heavy volumes of close,

1-5

accurate, and continuous fire

support to suppress and destroy

enemy personnel in support of an

attack.

• Serve as an integral part of a unit’s

defensive fire plan when

employing final protective fires by

breaking up and stopping an

enemy’s assault.

• Belt-fed

1-6

• Air-cooled

• Gas-operated

• Fully automatic

1800

1-7

a. Barrel assembly

1-8

b. Buttstock and buffer assembly

c. Drive spring rod assembly

d. Bolt and operating rod assembly

e. Trigger housing assembly

f. Cover assembly

g. Feed tray

h. Receiver assembly

1-9

Combination tool scraper and

1-16

extractor

1-16

Continued on next page

MCI Course 0321B

1-26

Study Unit 1, Lesson 1 Exercise

Lesson 1 Exercise, Continued

Answers,

continued

Item Number

Answer

Reference Page

• Feeding

1-19

• Chambering

• Locking

• Firing

• Unlocking

• Extracting

• Ejecting

• Cocking

Lesson

In this lesson, you have learned the purpose of the M240G medium

Summary

machinegun; the characteristics, capabilities, and nomenclature of the

weapon; the SL-3 components; and the functioning of the weapon.

In the next lesson, you will learn the procedures for clearing, disassembly,

assembly, and function check.

MCI Course 0321B

1-27

Study Unit 1, Lesson 1 Exercise

LESSON 2

CLEARING, DISASSEMBLY, ASSEMBLY, AND FUNCTION

CHECK

Introduction

Scope

To safely use and maintain the M240G medium machinegun and ensure it is

in good working order, you must know certain procedures. Being able to

properly disassemble and assemble the weapon is essential for maintaining

the weapon. Performing a function check is required to make sure that the

weapon functions properly after cleaning.

In this lesson, you will learn the procedures for clearing, disassembly,

assembly, and performing a function check of the M240G medium

machinegun.

Learning

After completing this lesson, you should be able to

Objectives

• Identify the steps for clearing the M240G medium machinegun.

• Identify the two categories of disassembly and assembly.

• Identify the sequence of steps for disassembling the M240G medium

machinegun.

• Identify the sequence of steps for assembling the M240G medium

machinegun.

• State when a function check should be performed.

• Identify the sequence of steps for performing a function check of the

M240G medium machinegun.

Continued on next page

MCI Course 0321B

1-29

Study Unit 1, Lesson 2

Clearing

Procedure

Before the weapon is handled or disassembled, it must be cleared. This

ensures the safety of the user and nearby personnel. The procedure for

properly clearing the M240G is listed in the table below:

Step

Action

Point the weapon in a safe direction, away from personnel.

Place the safety on “F” fire.

Pull the cocking handle to the rear to lock the bolt to the rear.

Push the cocking handle all the way forward.

Place the safety on “S” safe.

Continued on next page

MCI Course 0321B

1-31

Study Unit 1, Lesson 2

Clearing, Continued

Procedure,

continued

Step

Action

Push the cover latches in to release the cover and open the

cover assembly.

Remove any ammunition or links.

Raise the feed tray.

Visually and physically inspect the chamber to make sure it is

empty. If a round/cartridge is still in the chamber, remove the

round/cartridge as outlined in the troubleshooting section of

this course.

Continued on next page

MCI Course 0321B

1-32

Study Unit 1, Lesson 2

Disassembly

Introduction

The M240G is designed for easy disassembly—the use of force is not

necessary. No special tools are required. As the weapon is disassembled,

place the parts on a clean, flat surface. This reduces the possibility of losing a

part and aids in assembly. To prevent unnecessary wear, disassembly should

be kept to a minimum, consistent with maintenance and training

requirements.

Disassembly is divided into two categories—general and detailed. General

disassembly involves separating the weapon into main groups. This is also

known as field stripping. This allows the operator to quickly break the

weapon down into main components that can be hastily cleaned to keep the

weapon ready for action.

Detailed disassembly involves the removal of some component parts from

some of the main groups. This allows the operator to take more time to more

thoroughly clean the weapon. Complete general and detailed disassembly is

normal in garrison after field use or live fire but can also be done in a field

environment as necessary, to ensure the proper functioning and maintenance

of the weapon.

WARNING: Disassembly beyond the scope of this course, MCWP 3-15.1

Machineguns and Machinegun Gunnery, or TM

08670A/09712A-10/1B is not authorized, except by qualified

ordnance personnel.

General

Disassembly of the M240G medium machinegun begins with general

Disassembly

disassembly of the weapon into its five main groups in the following order:

• Barrel group

• Buttstock group

• Operating group

• Trigger housing group

• Receiver group

Note: Prior to disassembly of the M240G medium machinegun, ensure that

you have cleared the weapon.

Continued on next page

MCI Course 0321B

1-34

Study Unit 1, Lesson 2

Disassembly, Continued

Removing the

The procedure for removing the buttstock group is listed in the table below:

Buttstock

Group

Step

Action

Make sure the bolt is forward and raise the cover.

Depress the buttstock latch located on the underside of the

buttstock where it joins the receiver.

Slide the buttstock upward and remove it from the receiver.

Continued on next page

MCI Course 0321B

1-36

Study Unit 1, Lesson 2

Disassembly, Continued

Removing the

The procedure for removing the operating group is listed in the table below:

Operating

Group

Step

Action

Push in against the base of the drive spring rod assembly and

lift upward and out so that it clears the retaining studs inside the

receiver.

Remove the drive spring rod assembly from the receiver.

Continued on next page

MCI Course 0321B

1-37

Study Unit 1, Lesson 2

Disassembly, Continued

Removing the

Operating

Group,

continued

Step

Action

Pull the cocking handle to the rear.

Reach inside the top of the receiver and push rearward on the

face of the bolt with the index finger until the bolt and

operating rod assembly are exposed at the rear of the receiver.

Grasp the bolt and operating rod assembly and remove them

from the rear of the receiver.

Continued on next page

MCI Course 0321B

1-38

Study Unit 1, Lesson 2

Disassembly, Continued

Detailed

Detailed disassembly involves removing component parts of some of the

Disassembly

main groups. Detailed disassembly of these groups should be kept to a

minimum to reduce the possibility of damaging or losing parts. The buttstock

and trigger housing groups will not have a detailed disassembly performed by

the operator.

Operating

The operating group consists of the operating rod, bolt, and drive spring rod

Group

assembly. The bolt and operating rod assembly can have a detailed

disassembly performed by the operator. The procedures for performing

detailed disassembly on the bolt and operating rod are listed in the table

below.

Step

Action

Remove the spring-loaded pin (2) that holds the bolt (1) onto

the operating rod (3) as shown in the graphic below.

Pull the bolt forward until it is clear of the firing pin.

Continued on next page

MCI Course 0321B

1-40

Study Unit 1, Lesson 2

Disassembly, Continued

Barrel Group

The barrel group consists of the barrel with attached gas system, adjustable

front sight assembly, flash hider, and barrel carrying handle. The gas system

can have a detailed disassembly performed by the operator. The procedures

for performing the detailed disassembly are listed in the table below:

Step

Action

Hold the barrel at the point where the gas system attaches to it.

Push down and rotate the collar counterclockwise until it

releases from the gas plug.

Remove the collar from the gas plug.

Slide the gas plug to the rear and out of the gas regulator.

Continued on next page

MCI Course 0321B

1-41

Study Unit 1, Lesson 2

Disassembly, Continued

Receiver Group The receiver group consists of the receiver with rear sight, cover assembly,

feedtray, and bipod assembly. The cover assembly and feedtray can be

removed by the operator. The procedures for removing the cover assembly

and feedtray as listed in the table below:

Step

Action

Raise the cover straight up.

Pull the hinge spring pin out.

Lift the cover and feedtray from the receiver.

Note: Place cover down with moving parts facing up—moving

parts facing down can damage parts.

Note: This procedure completes general and detailed disassembly of the

M240G medium machinegun. Any further disassembly is not

authorized.

MCI Course 0321B

1-42

Study Unit 1, Lesson 2

Assembly

Detailed

Detailed assembly must be completed before general assembly of the weapon.

Detailed assembly is conducted on the operating group, barrel group, and

receiver group in any order.

Operating

The procedure for detailed assembly of the operating group is listed in the

Group

table below:

Step

Action

Hold the rod in one hand and slide the rear of the bolt over the

firing pin.

Align the holes on the bolt with those on the operating rod.

Push the spring loaded pin through the holes.

Barrel Group

The procedure for detailed assembly of the barrel group is listed in the table

below:

Step

Action

Insert the gas plug into the gas regulator.

Place the collar over the forward end of the gas plug.

Push against the collar while rotating clockwise until the collar

locks in place.

Receiver Group The procedure for detailed assembly of the receiver group is listed in the table

below:

Step

Action

Lay the feed tray on the receiver so the feed tray guides are

aligned with the receiver brackets.

Place the cover on the receiver aligning the mounting holes

with the mounting brackets on the receiver. Push the cover

down into the closed position.

Insert the cover hinge spring pin.

Continued on next page

MCI Course 0321B

1-43

Study Unit 1, Lesson 2

Assembly, Continued

General

General assembly is completed after detailed assembly. The process is the

reverse of general disassembly. The groups are assembled to the receiver

group in the following order:

• Trigger housing group

• Operating group

• Buttstock group

• Barrel group

Attaching the

The procedure for assembling the trigger housing group to the receiver group

Trigger

is listed in the table below:

Housing Group

Step

Action

Insert the holding notch on the front of the trigger housing into

its recesses on the bottom of the receiver.

Rotate the rear of the trigger housing group upward and align

the hole in the trigger housing with the mounting bracket on the

receiver.

Insert the trigger housing assembly spring pin into the hole.

Installing the

The procedure for assembling the operating group to the receiver group is

Operating

listed in the table below:

Group

Step

Action

Insert the bolt and operating rod into the receiver, aligning their

slots with the rails inside the receiver.

Extend the bolt to the unlock (forward) position.

Push the entire bolt and operating rod assembly into the

receiver.

Pull the trigger and continue to push the bolt and operating rod

all the way into the receiver.

Insert the drive spring rod assembly into the receiver aligning

the end with the recess in the rear of the operating rod.

Lower the drive spring rod assembly so that its base is seated

against the retaining stud inside the receiver.

Continued on next page

MCI Course 0321B

1-44

Study Unit 1, Lesson 2

Assembly, Continued

Attaching the

The procedure for assembling the buttstock group to the receiver group is

Buttstock

listed in the table below:

Group

Step

Action

Align the recessed grove at the front of the buttstock with the

vertical rails at the rear of the receiver.

Slide the buttstock downward until it locks in place.

Attaching the

The procedure for assembling the barrel group to the receiver group is listed

Barrel Group

in the table below.

Step

Action

Insert the barrel breach into the barrel socket on the receiver

aligning the gas plug with the gas cylinder.

Depress the barrel locking latch and fully seat the barrel in the

receiver.

Rotate the barrel carrying handle to the down position.

MCI Course 0321B

1-45

Study Unit 1, Lesson 2

Function Check

Purpose

The purpose of performing a function check is to ensure that the weapon is

working properly prior to use. Function checks should be done immediately

after any type of disassembly and assembly.

Procedure

The procedure for conducting a function check of the M240G medium

machinegun is listed in the table below:

Step

Action

Place the safety on “F” fire.

Pull the cocking handle to the rear and lock the bolt to the rear.

Return the cocking handle to the forward position.

Place the safety on “S” safe.

Pull the trigger; nothing should happen.

Place the safety on “F” fire.

Pull and hold the cocking handle to the rear.

Pull the trigger and ease the bolt forward until it locks.

MCI Course 0321B

1-46

Study Unit 1, Lesson 2

Lesson 2 Exercise

Directions

Complete exercise items 1 through 13 by performing the action required.

Check your answers against those listed at the end of this lesson.

Item 1

List the steps for clearing the M240G medium machinegun.

___________________________________________________________

10. ___________________________________________________________

11. ___________________________________________________________

12. ___________________________________________________________

Item 2

The two categories of disassembly are

a. operator and upper echelon.

b. authorized and unauthorized.

c. general and detailed.

d. field and garrison.

Continued on next page

MCI Course 0321B

1-47

Study Unit 1, Lesson 2 Exercise

Lesson 2 Exercise, Continued

Item 3

To ensure the safety of the operator, prior to disassembling the M240G

medium machinegun, the operator should

a. clean the weapon.

b. clear the weapon to ensure it is not loaded.

c. make sure the rear sight is in the down position.

d. change the barrels.

Items 4

Matching: For items 4 through 7, match the letter of the component groups

Through 7

from column 2 to column 1 in the proper order they are disassembled from

the receiver group when performing general disassembly.

Column 1

Column 2

Order

Group

___ 4.

a. Barrel

___ 5.

b. Trigger housing

___ 6.

c. Buttstock

___ 7.

d. Operating

Items 8

Matching: For items 8 through 11, match the letter of the component groups

Through 11

from column 2 to column 1 in the proper order they are assembled to the

receiver group when performing general assembly.

Column 1

Column 2

Order

Group

___ 8.

a. Trigger housing

___ 9.

b. Buttstock

___ 10.

c. Operating

___ 11.

d. Barrel

Continued on next page

MCI Course 0321B

1-48

Study Unit 1, Lesson 2 Exercise

Lesson 2 Exercise, Continued

Item 12

After completing disassembly and assembly, the operator should

a. return the M240G to the armory.

b. place the M240G in the gun bag.

c. change the barrels.

d. perform a function check.

Item 13

List the steps for performing a function check for the M240G medium

machinegun.

___________________________________________________________

Continued on next page

MCI Course 0321B

1-49

Study Unit 1, Lesson 2 Exercise

Lesson 2 Exercise, Continued

Answers

The table below provides the answers to the exercise items. If you have any

questions, refer to the reference page listed for each item.

Item Number

Answer

Reference Page

1. Point the weapon in a safe direction,

1-31

away from personnel.

through

2. Place the safety on “F” fire.

1-33

3. Pull the cocking handle to the rear

to lock the bolt to the rear. Push the

cocking handle all the forward.

4. Place the safety on “S” safe.

5. Push the cover latches in to release

the cover and open the cover

assembly.

6. Remove any ammunition or links.

7. Raise the feed tray.

8. Visually and physically inspect the

chamber to make sure it is empty.

If a round/cartridge is still in the

chamber, remove the

round/cartridge.

9. Lower the feed tray.

10. Place the safety on “F” fire.

11. Pull the cocking handle to the rear

and hold it. Pull the trigger and

ease the bolt forward ensuring that

it locks and the cocking handle is all

the way forward.

12. Close the cover.

1-34

1-44

Continued on next page

MCI Course 0321B

1-50

Study Unit 1, Lesson 2 Exercise

Lesson 2 Exercise, Continued

Answers,

continued

Item Number

Answer

Reference Page

1-44

1-46

1. Place the safety on “F” fire.

1-46

2. Pull the cocking handle to the rear

and lock the bolt to the rear. Return

the cocking handle to the forward

position.

3. Place the safety on “S” safe.

4. Pull the trigger; nothing should

happen.

5. Place the safety on “F” fire.

6. Pull and hold the cocking handle to

the rear.

7. Pull the trigger and ease the bolt

forward until it locks.

Lesson

In this lesson, you have learned the procedures for clearing the M240G,

Summary

performing disassembly and assembly, and conducting a function check.

In the next lesson, you will learn about the ammunition used with the M240G

medium machinegun.

MCI Course 0321B

1-51

Study Unit 1, Lesson 2 Exercise

LESSON 3

AMMUNITION

Introduction

Scope

Another aspect of employing the M240G medium machinegun is knowing

which type of ammunition to use.

In this lesson, you will learn the different types of ammunition used with the

M240G, how to identify the ammunition, and the purpose of each type. In

addition, you will also learn how to properly store and handle the

ammunition.

Learning

After completing this lesson, you should be able to

Objectives

• Identify the types of ammunition used with the M240G medium

machinegun.

• Identify the purpose of the different types of ammunition used with the

M240G medium machinegun.

• Identify the guidelines when storing M240G ammunition.

• Identify the guidelines when handling the M240G ammunition.

In This Lesson This lesson contains the following topics:

Topic

See Page

Introduction

1-53

Ammunition

1-54

Ammunition Storage and Handling

1-56

Lesson 3 Exercise

1-58

MCI Course 0321B

1-53

Study Unit 1, Lesson 3

Ammunition

Characteristics The ammunition used for the M240G medium machinegun has the following

common characteristics:

•

7.62 mm NATO cartridge

• Uses a disintegrating metallic split-link belt

• Linked in 100-round bandoleers (belts) that weigh approximately 7 pounds

Types

There are five different types of M240G medium machinegun 7.62mm

ammunition.

• M80 ball

• M62 tracer

• M82 blank

• M63 dummy

• M61 armor-piercing

M80 Ball

The M80 ball 7.62 mm cartridge is identified by a plain bullet tip with a full

metal jacket. It is used for marksmanship training, anti-personnel, and light

material targets. The M80 ball is the non-tracer component used in the 4 and

1 combat mix.

M62 Tracer

The M62 tracer 7.62 mm cartridge is identified by an orange bullet tip. It is

used for the observation of fire, incendiary effects, signaling, and marking

targets. The M62 tracer is the tracer component of the 4 and 1 combat mix.

Continued on next page

MCI Course 0321B

1-54

Study Unit 1, Lesson 3

Ammunition, Continued

M82 Blank

The M82 blank cartridge is identified by the absence of a bullet and a double-

tapered neck, only a sealed metal casing. It is used with a special adapter to

simulate live-fire during training.

M63 Dummy The M63 dummy cartridge is identified by a plain bullet, six longitudinal

corrugations (flutings) along the casing, and the absence of a vent hole in the

primer pocket. It is used for training purposes such as loading, unloading,

and gun drills.

M61 Armor-

The M61 armor-piercing is identified by a black bullet tip. It is used against

Piercing

lightly armored targets where armor penetration effects are desired.

Armor

The table below details the armor penetration of the M80 ball and M61

Penetration

armor-piercing ammunition.

Armor Penetration

Ammunition Type

300 Meters

500 Meters

M80 ball

4mm

3mm

M61 armor-piercing

7mm

5mm

MCI Course 0321B

1-55

Study Unit 1, Lesson 3

Ammunition Storage and Handling

Ammunition

The following guidelines should be followed when storing M240G

Storage

ammunition:

• Store away from heat sources such as open flame, radiators, heaters, and

hot water pipes.

• Do not store ammunition in the direct rays of the sun for long periods. If

the powder is hot, excessive pressure may be developed when the weapon

is fired.

• If stored outdoors in the open, keep the ammunition at least six inches off

the ground and covered with tarp. Use materials to keep the tarp elevated

off the ammunition to allow free air circulation.

Ammunition

The following guidelines should be followed when handling M240G

Handling

ammunition.

• Ammunition containers should not be opened until the ammunition is to

be used. Ammunition removed from containers in damp environments

can corrode.

• Protect the ammunition from mud, dirt, and water. If the ammunition gets

wet or dirty, wipe it off prior to use.

• Wipe off light corrosion when it is discovered. Ammunition that is

heavily corroded should be replaced.

Continued on next page

MCI Course 0321B

1-56

Study Unit 1, Lesson 3

Ammunition Storage and Handling, Continued

Ammunition

The following guidelines should be followed during live-fire of the M240G:

Handling When

Firing

• Avoid getting the ammunition in the dirt when firing. The ammunition

can pick up pieces of dirt that can cause a weapon to malfunction.

• Do not oil or grease the ammunition. Dust and other abrasives will collect

on it and could damage the operating parts of the weapon.

• Do not fire dented cartridges, cartridges with loose projectiles, or other

defective rounds.

• Do not fire over friendly troops with ammunition marked as FOR

TRAINING PURPOSES ONLY. Special lots of ammunition are

approved for overhead fire and are marked FOR OVERHEAD FIRE.

• Do not fire ammunition, other than blank ammunition, that cannot be

identified by type (i.e., the colored marking is rubbed off).

MCI Course 0321B

1-57

Study Unit 1, Lesson 3

Lesson 3 Exercise

Directions

Complete exercise items 1 through 8 by performing the action required.

Check your answers against those listed at the end of this lesson.

Item 1

List the five types of ammunition used with the M240G medium machinegun.

•

___________________________________________________________

•

___________________________________________________________

•

___________________________________________________________

•

___________________________________________________________

•

___________________________________________________________

Item 2

What is the purpose of M80 ball ammunition?

______________________________________________________________

Item 3

What is the purpose of M62 tracer ammunition?

______________________________________________________________

Item 4

What is the purpose of M82 blank ammunition?

______________________________________________________________

Continued on next page

MCI Course 0321B

1-58

Study Unit 1, Lesson 3 Exercise

Lesson 3 Exercise, Continued

Item 5

What is the purpose of M63 dummy ammunition?

______________________________________________________________

Item 6

What is the purpose of M61 armor-piercing ammunition?

______________________________________________________________

Item 7

Which of the following is a storage consideration when storing M240G

ammunition?

a. Store ammunition near heat sources.

b. Store ammunition away from heat sources.

c. Store ammunition at least 6 inches off the ground and cover with tarps to

restrict air circulation.

d. Store ammunition in the direct rays of the sun.

Item 8

Which of the following is a consideration when handling M240G ammunition

during live fires?

a. You should oil or grease the ammunition to aid in operation.

b. You should fire dented cartridges, cartridges with loose projectiles, or

other defective rounds.

c. You should avoid getting the ammunition in the dirt when firing.

d. It is acceptable to fire ammunition, other than blank ammunition, that

cannot be identified by type (i.e., the colored marking is rubbed off).

Continued on next page

MCI Course 0321B

1-59

Study Unit 1, Lesson 3 Exercise

Lesson 3 Exercise, Continued

Answers

The table below provides the answers to the exercise items. If you have any

questions, refer to the reference page listed for each item.

Item Number

Answer

Reference Page

• M80 ball

1-54

• M62 tracer

• M82 blank

• M63 dummy

• M61 armor-piercing

Marksmanship training, anti-personnel,

1-54

and light material targets.

Observation of fire, incendiary effects,

1-54

signaling, and marking targets.

Simulate live-fire during training.

1-55

Training purposes such as loading,

1-55

unloading, and gun drills.

Against lightly armored targets where

1-55

armor penetration effects are desired.

1-56

1-57

Lesson

In this lesson, you learned the different types of ammunition, how to identify

Summary

them, and their purpose. You also learned considerations when storing and

handling M240G ammunition.

Study Unit 1

In this study unit, you have learned the characteristics, nomenclature,

Summary

functioning, and ammunition used with the M240G medium machinegun.

Also, you learned the procedures to clear, disassemble, assemble, and perform

a function check.

In the next study unit, you will learn how to maintain the weapon and its

associated equipment.

MCI Course 0321B

1-60

Study Unit 1, Lesson 3 Exercise

STUDY UNIT 2

MAINTENANCE

Overview

Scope

Having a weapon that is clean and functioning properly is paramount to the

success of your mission. To ensure the M240G is ready for combat, you need

to know how to properly clean and inspect it for damage.

In this study unit, you will learn how to properly care for the M240G medium

machinegun. This includes the authorized cleaning materials to use, how to

clean and inspect each main group of the M240G, and how to care for the

associate components such as the tripod, mount, and carrying bags.

In This Study

This study unit contains the following lessons:

Unit

Lesson

See Page

Cleaning Materials and Lubricants

2-3

Caring for the M240G Medium Machinegun

2-9

Caring for the SL-3 Components

2-29

MCI Course 0321B

2-1

Study Unit 2

LESSON 1

CLEANING MATERIALS AND LUBRICANTS

Introduction

Scope

Cleaning the weapon is important to ensure it is in good working condition.

Using the wrong materials or the wrong lubrication can cause damage that

can render the M240G useless.

In this lesson, you will learn what materials are authorized to clean the

M240G, what lubricants to use, and under what conditions each lubricant

should be used.

Learning

After completing this lesson, you should be able to

Objectives

• Identify the authorized cleaning materials for the M240G medium

machinegun.

• Identify the authorized lubricants for the M240G medium machinegun.

• Identify which lubricants should be used under certain temperatures.

In This Lesson This lesson contains the following topics:

Topic

See Page

Introduction

2-3

Cleaning Materials

2-4

Lubricants

2-5

Lesson 1 Exercise

2-6

MCI Course 0321B

2-3

Study Unit 2, Lesson 1

Cleaning Materials

Authorized

Only three cleaning agents are authorized for use when cleaning the M240G

Cleaning

medium machinegun:

Agents

• CLP (cleaner, lubricant, and preservative)

• RBC (rifle bore cleaner)

• Dry cleaning solvent

CLP

Cleaner, lubricant, and preservative is used for general cleaning, carbon

removal, and corrosion removal.

RBC

Rifle bore cleaner is used for general cleaning, carbon removal, and corrosion

removal in the chamber and barrel areas.

Dry Cleaning

Dry cleaning solvent is a chemical used to remove lubricants and other

Solvent

cleaning agents from the weapon. Use dry cleaning solvent to remove

lubricants from the weapon when changing from one lubricant to another.

MCI Course 0321B

2-4

Study Unit 2, Lesson 1

Lubricants

Authorized

Lubricants are used on the M240G medium machinegun on certain operating

Lubricants

parts before, during, and after operation. The lubrication aids in the operation

of the weapon and helps to protect it from corrosion. Only the lubricants

listed below are authorized for use on the M240G medium machinegun:

• CLP (cleaner, lubricant, and preservative)

• LSA (lubricating oil, semi-fluid)

• LSA-T (lubricating oil, semi-fluid with Teflon)

• LAW (lubricating oil, arctic weather)

Lubricant Use

CLP, LSA, or LSA-T should be used under all but the coldest arctic

conditions:

MCI Course 0321B

2-5

Study Unit 2, Lesson 1

Lesson 1 Exercise

Directions

Complete exercise items 1 through 3 by performing the action required.

Check your answers against those listed at the end of this lesson.

Item 1

List the authorized cleaning materials for use on the M240G medium

machinegun.

•

___________________________________________________________

•

___________________________________________________________

•

___________________________________________________________

Item 2

List the authorized lubricants for use on the M240G medium machinegun.

•

___________________________________________________________

•

___________________________________________________________

•

___________________________________________________________

•

___________________________________________________________

Item 3

Which lubricant should be used when the normal outside temperature is

+10°F (-12°C) or below?

a. CLP

b. LSA

c. LSA-T

d. LAW

Continued on next page

MCI Course 0321B

2-6

Study Unit 2, Lesson 1 Exercise

Lesson 1 Exercise, Continued

Answers

The table below lists the answers to the exercise items. If you have questions

about the items, refer to the reference page.

Item Number

Answer

Reference Page

• CLP

2-4

• RBC

• Dry cleaning solvent

• CLP

2-5

• LSA

• LSA-T

• LAW

2-5

Summary

In this lesson, you have learned what items are used to clean and lubricate the

M240G as well as which lubricants to use under what conditions.

In the next lesson, you will learn how to properly care for the M240G

medium machinegun.

MCI Course 0321B

2-7

Study Unit 2, Lesson 1 Exercise

LESSON 2

CARING FOR THE M240G MEDIUM MACHINEGUN

Introduction

Scope

Not maintaining the M240G correctly can result in poor weapon performance

or even failure. As an operator of the M240G medium machinegun, it is your

responsibility to keep the weapon clean and operational at all times.

In this lesson, you will learn how to properly clean, lubricate, and inspect

each group of the M240G. You will also learn how to perform a function

check to ensure the machinegun is working properly. In addition, the

required care before, during, and after firing will also be covered.

Learning

After completing this lesson, you should be able to

Objectives

• List general maintenance guidelines.

• Identify the steps for maintaining the different groups of the M240G.

• Identify the steps for inspecting the M240G.

• Identify the steps for care before, during, and after firing.

• Identify the steps for checking the headspace.

Continued on next page

MCI Course 0321B

2-9

Study Unit 2, Lesson 2

Introduction, Continued

In This Lesson This lesson contains the following topics:

Topic

See Page

Introduction

2-9

Operator Maintenance Guidelines

2-11

Barrel Group

2-12

Buttstock and Buffer Group

2-17

Operating Group

2-18

Trigger Group

2-20

Receiver Group

2-21

Care and Cleaning Before, During, and After Firing

2-24

Lesson 2 Exercise

2-25

MCI Course 0321B

2-10

Study Unit 2, Lesson 2

Operator Maintenance Guidelines

Precautions

When cleaning the M240G medium machinegun, follow these guidelines:

• Use care when removing excess carbon from the weapon. Carbon may

chip off and fly into the eyes. Protective goggles should be worn.

• Using cleaning materials other than those listed in the previous section

such as gasoline, kerosene, hydraulic oil, benzene, bensol, or high-pressure

water is prohibited.

• Do not use abrasives to clean the bore, piston, gas cylinder, or gas

regulator plug.

• Do not apply lubricants to composite or rubber components.

• Do not apply dry solvent to plastic parts.

Non-Use

If the M240G is not used, it should still be maintained (cleaned and

lubricated) at least every 90 days.

Preparation

Before cleaning the M240G medium machinegun, do the following:

• Clear the weapon.

• Perform general and detailed disassembly on the weapon.

• To ensure thorough cleaning, clean the M240G one group at a time.

Note: Upon completion of operator maintenance, be sure to perform a

function check after assembling the weapon.

Continued on next page

MCI Course 0321B

2-11

Study Unit 2, Lesson 2

Barrel Group

Gas Regulator Use the procedure in the table below to maintain the gas regulator plug:

Plug

Step

Action

Using the scraper tool, insert the scraper into the center hole of

the gas regulator plug as shown below. Twist the scraper

clockwise to remove carbon from the center hole until the

scraper is fully seated against the gas regulator plug.

Fold the scraper over and press the scraper point into the

groove. Turn the gas regulator plug clockwise to remove

carbon from the groove.

Continued on next page

MCI Course 0321B

2-12

Study Unit 2, Lesson 2

Barrel Group, Continued

Gas Regulator

Plug, continued

Step

Action

Pivot the scraper blade 180° to the opposite side and place the

scraper point into the groove of the gas regulator plug. Turn

the gas regulator plug clockwise to remove carbon from the

groove.

Using the tip of the scraper, scrape carbon from the surface of

the gas regulator plug.

Continued on next page

MCI Course 0321B

2-13

Study Unit 2, Lesson 2

Barrel Group, Continued

Maintaining

Use the procedure in the table below to maintain the barrels. Make sure the

procedure is done to both barrels:

Step

Action

Insert the large reamer through the hole in the gas port busing

into the gas port hole in the barrel. Twist the reamer back-and-

forth until the reamer enters the bore of the barrel to remove

carbon.

Remove carbon, dirt, and corrosion from the bore and chamber

using the cleaning rod with the bore brush, chamber brush, and

swabs dampened with CLP or RBC.

Clean the remaining parts of the barrel using a soft bristle brush

and wiping rag dampened with CLP.

Lubricate the barrel surfaces with CLP, LSA, or LSA-T.

• Apply a light coat of lubricant to all metal surfaces.

• Apply a light coat of lubricant to the bore using the

cleaning rod and a swab lightly moistened with lubricant.

Assemble the barrel group. Make sure the gas regulator plug is

set to 1 and facing the barrel before securing it with the gas

collar.

MCI Course 0321B

2-15

Study Unit 2, Lesson 2

Barrel Group, Continued

Inspecting

When inspecting the barrel group, look for the following:

• Cracks, dents, or metal burrs which may hinder the operation of the

weapon

• Obstructions in the bore or chamber of the barrel

• Damage to the front sight

• Damage to the barrel carrying handle, bracket, or bracket latch

• Damage to the flash hider

• Buffer plug damage

MCI Course 0321B

2-16

Study Unit 2, Lesson 2

Buttstock and Buffer Group

Maintaining

Use the procedure in the table below to maintain the trigger housing group:

Step

Action

Clean the metal parts: stock rails, buttstock latch, buttplate,

and rear sling attachment with CLP to remove any corrosion

and carbon residue.

Clean the composite/plastic parts with a damp wiping rag

removing any dirt or carbon residue.

Lubricate the buttstock and buffer assembly. Make sure

lubricant does not get on composite/plastic parts. Lightly

lubricate the

• Stock rails

• Buttstock latch

• Buttplate and rear sling attachment to prevent corrosion

Inspecting

When inspecting the buttstock and buffer group, look for the following:

• Loose fit when the buttstock assembly is attached to the receiver

• Proper operation of the buttstock latch

• Damage to the rear sling attachment

• Buffer plug sticking out 1/8 inch (weapon will not function.)

MCI Course 0321B

2-17

Study Unit 2, Lesson 2

Operating Group

Maintaining

Use the procedure in the table below to maintain the operating group:

Step

Action

Insert the combination tool into the cavity of the piston on the

operating rod. Squeeze the handle firmly while twisting the

combination tool back-and-forth to remove carbon from the

sides of the cavity.

Insert the screwdriver end of the combination tool into the

cavity of the piston on the operating rod. Twist back-and-forth

to remove carbon in the bottom of the cavity.

Continued on next page

MCI Course 0321B

2-18

Study Unit 2, Lesson 2

Operating Group, Continued

Maintaining,

continued

Step

Action

Clean the remaining portions of the operating group to include

the operating rod, firing pin, bolt, and driving spring using an

all-purpose brush moistened with CLP and a wiping rag.

Apply a thin coat of lubricant to the operating group:

• Bolt and operating rod moving parts

• Polished areas

• Firing pin

• Linear roller

• Driving spring

Assemble the operating group.

Inspecting

When inspecting the operating group, look for the following:

• Burrs, cracks, broken pins or a frozen linear roller on the bolt and

operating rod.

• Broken strands on the driving spring. If two or more strands are broken

on the same coil or three or more strands are broken in any location,

notify unit maintenance.

MCI Course 0321B

2-19

Study Unit 2, Lesson 2

Trigger Housing Group

Maintaining

Use the procedure in the table below to maintain the trigger housing group:

Step

Action

Clean the internal parts with a cotton swab moistened with CLP

or RBC to remove any carbon residue.

Clean the outside with a cleaning rag.

Lubricate the internal moving parts including tripping lever,

sear, trigger, and trigger housing spring pin with a light coat of

lubricant.

Inspecting

When inspecting the trigger housing group, look for the following:

• Broken or damaged trigger housing lug.

• Broken, cracked, or missing grips.

• Make sure trigger guard is not bent and interferes with trigger operation.

• Burrs, cracks, or wear on the tripping lever and sear.

• Test cocking action by pushing back on the tripping lever then pulling

trigger.

• Test safety function. Place safety on SAFE, pull trigger, sear should not

lower. Place safety on FIRE, pull trigger, sear should lower.

MCI Course 0321B

2-20

Study Unit 2, Lesson 2

Receiver Group

Maintaining

Use the procedure in the table below to maintain the receiver group:

Step

Action

Remove carbon from inside of cover assembly using wiping

rags and swaps moistened with CLP. Pay close attention to the

moving parts such as the feed pawls and feed lever.

Clean the top of the cover and accessory mounting rails with a

wiping rag and all-purpose brush moistened with CLP.

Carefully insert the combination tool into the fore end of the

gas cylinder of the receiver body.

Make sure the combination tool is fully seated in the gas

cylinder. Apply slight pressure to the handles and twist back-

and-forth to remove carbon.

Continued on next page

MCI Course 0321B

2-21

Study Unit 2, Lesson 2

Receiver Group, Continued

Maintaining,

continued

Step

Action

Clean the gas cylinder bore with the gas cylinder brush

moistened with CLP or RBC.

Clean the remainder of the receiver group to include the

receiver body, rear sight, and bipods.

Lightly lubricate the receiver group:

• Moving parts of the cover assembly

• Moving parts of the receiver body

• Rails inside the receiver body

• Moving parts of the bipod assembly

Continued on next page

MCI Course 0321B

2-22

Study Unit 2, Lesson 2

Receiver Group, Continued

Inspecting

When inspecting the receiver group, check the following:

• Proper operation of the bipod latch

• Proper operation of the bipod assembly

• Spring tension on the front and rear feed pawls (press on them.)

• Spring tension on the feed arm (move it back and forth.)

• Spring tension on the cartridge guides

• Excessive wear of the moving parts of the cover

• Proper operation of the cover latches

• Damage to the mounting rail on the cover

• Spring tension and operation of the barrel locking latch

• Smooth operation of the cocking handle

• Damage on the rear sight assembly

• Operation of the rear sight assembly

MCI Course 0321B

2-23

Study Unit 2, Lesson 2

Care and Cleaning Before, During, and After Firing

Before Firing

Before firing the M240G, the operator should

• Inspect the M240G for cleanliness, proper mechanical condition (function

check), and missing or broken parts.

• Remove excess lubricant from the bore, chamber, barrel socket, and face

of the bolt.

• Apply lubricant on the recesses of the operating rod that make contact with

the receiver rails.

• Lightly lubricate the spring pin, roller, and other moving parts of the bolt.

• Lubricate the receiver by pulling the bolt to the rear with the cocking

handle and running a line of lubricant on either side of the bolt. Manually

pull the bolt back and forth to spread the lubricant over the bolt and

receiver rails.

Check

Check the headspace of both barrels by rotating the barrel handle and

Headspace

counting the number of clicks heard. There should be a minimum of two

clicks and a maximum of seven. If there are less than two or more than

seven, the weapon should not be fired, but turned in for higher level

maintenance.

During Firing

Maintain a light coat of lubrication on the areas that were lubricated prior to

firing. Ensure the gas system remains tight. Change barrels when necessary.

After Firing

After firing the M240G, the operator should

• Perform operator maintenance for three consecutive days. After cleaning

each day, all cleaning materials should be wiped off the weapon. Then,

place a light coat of CLP on all metal surfaces.

• If the weapon is fired daily, general cleaning should be performed on the

weapon broken down into the five main groups. Repeated detailed

disassembly will cause unnecessary wear.

MCI Course 0321B

2-24

Study Unit 2, Lesson 2

Lesson 2 Exercise

Directions

Complete exercise items 1 through 6 by performing the action required.

Check your answers against those listed at the end of this lesson.

Item 1

Before performing maintenance on the M240G medium machinegun, the

operator should

a. request authorization from the section leader.

b. soak the entire machinegun in dry cleaning solvent for one hour.

c. fire the machinegun so that it is dirty.

d. clear the weapon prior to disassembling it.

Item 2

When cleaning the gas regulator plug, the operator should use ____________

to remove carbon.

a. the scraper tool

b. a screwdriver

c. steel wool

d. abrasive cleaners

Item 3

How many strands can be broken on a single coil of the driving spring before

it should be replaced?

Continued on next page

MCI Course 0321B

2-25

Study Unit 2, Lesson 2 Exercise

Lesson 2 Exercise, Continued

Item 4

Prior to firing the M240G, the operator should remove excess lubricant from

the

a. front and rear sight assemblies.

b. belt of ammunition.

c. bore, chamber, barrel socket, and face of the bolt.

d. barrel surface.

Item 5

When checking the headspace on the M240G, there should be between

________ and ________ clicks.

1; 5

2; 5

1; 7

2; 7

Continued on next page

MCI Course 0321B

2-26

Study Unit 2, Lesson 2 Exercise

Lesson 2 Exercise, Continued

Answers

The table below lists the answers to the exercise items. If you have questions

about the items, refer to the reference page.

Item Number

Answer

Reference Page

2-11

2-12

2-19

2-24

Summary

In this lesson, you have learned how to properly care for the M240G medium

machinegun.

In the next lesson, you will learn how to care for the associated components

such as the M122 tripod and the flex-mount/T&E mechanism.

MCI Course 0321B

2-27

Study Unit 2, Lesson 2 Exercise

LESSON 3

CARING FOR THE SL-3 COMPONENTS

Introduction

Scope

Often, the associated components are needed to help accomplish the mission

with the M240G. If the tripod or mount fails during combat, it can have

serious consequences on the outcome of the mission.

In this lesson, you will learn how to care for the associate components of the

M240G medium machinegun.

Learning

Upon completion of this lesson, you should be able to

Objectives

• Identify the procedures for caring for the M122 tripod.

• Identify the procedures for caring for the flex-mount/T&E mechanism.

• Identify the procedures for caring for the carrying bag and the spare barrel

bag.

In This Lesson This lesson contains the following topics.

Topic

See Page

Introduction

2-29

M122 Tripod

2-30

Flex-Mount/T&E Mechanism

2-31

Carrying Bag and Spare Barrel Bag

2-32

Lesson 3 Exercise

2-33

MCI Course 0321B

2-29

Study Unit 2, Lesson 3

M122 Tripod

Cleaning

To clean the M122 tripod, do the following:

• Remove all dirt using a soft bristle brush and a damp wiping rag.

• Remove any corrosion using a soft bristle brush dampened with CLP.

Inspecting

Inspect the following areas on the M122 tripod:

• Rear legs expand properly and lock in place

• Sleeve latch functions properly

• Front leg folds out properly

• Legs are not bent

• Markings on the traverse slide bar are legible

• Pintle lock functions by locking the flex-mount onto the tripod head

Lubricating

Lubricate the M122 tripod using the same guidelines for the M240G medium

machinegun. Lightly lubricate the following areas of the tripod:

• Pintle lock assembly

• Sleeve latch

• Moving parts of the sleeve and portion of the legs on which the sleeves

slide

MCI Course 0321B

2-30

Study Unit 2, Lesson 3

Flex-Mount/T&E Mechanism

Cleaning

To clean the flex-mount/T&E mechanism, do the following:

• Remove all dirt with a soft bristle brush and a damp wiping rag.

• Remove any corrosion with a soft bristle brush dampened with CLP.

• Extend the T&E mechanism to clean the entire length of both the upper

and lower elevating screws.

• Turn the traversing handwheel all the way in both directions to clean the

entire traversing screw.

Inspecting

Inspect the following areas on the flex-mount/T&E mechanism:

• Pintle for excessive wear or burrs that may interfere with its fit into the

tripod

• Pivot points on the flex-mount so

• that they move freely

• Brass deflector is not bent up to obstruct the ejection of brass during

operation

• Traversing handwheel for smooth operation and dead clicks

• Elevating handwheel for smooth operation and dead clicks

• Elevation and traverse scales can be read without difficulty

• Traversing slide lock lever or proper operation

Lubricating

Lubricate the flex-mount/T&E mechanism using the same guidelines for the

M240G medium machinegun. Lightly lubricate the flex-mount/T&E

mechanism:

• Pivot points on the flex-mount

• Entire length of the upper and lower elevating screws

• Entire traversing screw

• Pivot point on the traversing slide lock lever

MCI Course 0321B

2-31

Study Unit 2, Lesson 3

Carrying Bag and Spare Barrel Bag

Cleaning

To clean the bags, use the following guidelines:

• Remove any dirt or mud with a stiff bristle brush.

• Wash the bags with a mild detergent and cold or warm water. Rinse

thoroughly with clean water.

• Air dry the bags in the shade or indoors.

• Do not wash in hot water.

• Do not wash or dry in laundry machines.

• Do not use chlorine bleach, yellow soap, cleaning fluids, or solvents to

clean the bags.

• Do not dry in direct sunlight, direct or extreme heat, or with an open

flame.

• Do not attempt to dye or repair the bags. Turn them in for replacement.

Inspecting

Inspect the following on the carrying and spare barrel bags:

• Excessive wear

• Closures on both bags for serviceability

• Retaining straps for serviceability

• Carrying straps for serviceability

MCI Course 0321B

2-32

Study Unit 2, Lesson 3

Lesson 3 Exercise

Directions

Complete exercise items 1 through 3 by performing the action required.

Check your answers against those listed at the end of this lesson.

Item 1

When caring for the M122 tripod, what are the three areas you should

lubricate?

•

___________________________________________________________

•

___________________________________________________________

•

___________________________________________________________

Item 2

When caring for the T&E mechanism, what two components should be

checked for smooth operation and dead clicks?

•

___________________________________________________________

•

___________________________________________________________

Item 3

When cleaning the carrying bag or spare barrel bag, do not

•

___________________________________________________________

•

___________________________________________________________

•

___________________________________________________________

•

___________________________________________________________

•

___________________________________________________________

Continued on next page

MCI Course 0321B

2-33

Study Unit 2, Lesson 3

Lesson 3 Exercise, Continued

Answers

The table below provides the answers to the exercise items. If you have any

questions, refer to the reference page listed for each item.

Item Number

Answer

Reference Page

• Pintle latch assembly

2-30

• Sleeve latch

• Portion of legs on which the

sleeves move

• Traversing handwheel

2-31

• Elevating handwheel

• Do not wash in hot water.

2-32

• Do not wash or dry in laundry

machines.

• Do not use chlorine bleach, yellow

soap, cleaning fluids, or solvents

to clean the bags.

• Do not dry in direct sunlight,

direct or extreme heat, or with an

open flame.

• Do not attempt to dye or repair the

bags.

Lesson

In this lesson, you learned how to properly care for the M122 tripod, flex-

Summary

mount/T&E mechanism, and the carrying bags.

Study Unit 2

In this study unit, you learned which cleaning materials and lubricants are

Summary

authorized for use on the M240G medium machinegun. Also, you learned

how to properly clean, inspect, and lubricate the different parts of the weapon

and its associated components. Proper cleaning with the proper materials is

instrumental in keeping the M240G medium machinegun operational and in

the fight.

In the next study unit, you will learn how to mount, load, zero, operate, and

troubleshoot the M240G.

MCI Course 0321B

2-34

Study Unit 2, Lesson 3

STUDY UNIT 3

OPERATING THE M240G MEDIUM MACHINEGUN

Overview

Scope

Proper operation of the M240G is the key to a successful mission. As the

operator, you need to know how to properly setup and load the weapon to get

accurate fire on your targets as quickly as possible. The mission may depend

on your ability to accurately suppress the enemy and destroy targets. If your

M240G stops working, you have to be able to identify the problem, correct it,

and get your weapon back in action with minimal down time.

In this study unit, you will learn how to mount the M240G on bipod and

tripod mounts; loading and unloading procedures; how to fire the weapon;

how to zero the weapon; and how to troubleshoot problems if something goes

wrong.

In This Study

This study unit contains the following lessons:

Unit

Lesson

See Page

Mounting

3-3

Loading and Unloading

3-19

Firing

3-27

Zeroing

3-47

Troubleshooting

3-57

MCI Course 0321B

3-1

Study Unit 3

LESSON 1

MOUNTING

Introduction

Scope

Being able to operate the M240G and provide accurate fire is essential to the

mission. Hollywood has portrayed automatic weapons as being effective

when fired as the action star is running into combat—each round hitting its

intended target every time. The truth is automatic weapons are only effective

and accurate when they have a stable base to fire from.

In this lesson, you will learn how to properly set up the M240G for firing

from the attached bipod and the M122 tripod.

Learning

Upon completion of this lesson, you will be able to

Objectives

• List the steps for setting up the M240G with the bipod mount.

• List the steps for setting up the M240G with the tripod mount.

• List the steps for preparing the T&E mechanism.

In This Lesson This lesson contains the following topics:

Topic

See Page

Introduction

3-3

Using the Bipod

3-4

Using the Tripod

3-7

Lesson 1 Exercise

3-17

MCI Course 0321B

3-3

Study Unit 3, Lesson 1

Using the Bipod

The Bipod

The bipod is permanently attached to the M240G and is a part of the receiver

group. The bipod is attached to the receiver by a ball joint that allows limited

movement.

Lowering the

Use the steps listed in the table below to lower the bipod:

Bipod

Step

Action

Grasp the bipod and push in on the bipod latch.

Rotate the bipod legs down and forward.

Continued on next page

MCI Course 0321B

3-4

Study Unit 3, Lesson 1

Using the Tripod

The Tripod

The tripod mount consists of the M122 tripod and the flex-mount with T&E

Mount

mechanism. The tripod provides a stable and lightweight base that is far

superior to the bipod. The tripod is the preferred method of employment.

Setting up the

The steps for setting up the tripod are listed in the table below:

Tripod

Step

Action

Spread the rear tripod legs apart to extend them.

Continue until the sleeve latch engages, locking them in the

open position.

Continued on next page

MCI Course 0321B

3-7

Study Unit 3, Lesson 1

Using the Tripod, Continued

Preparing the

The steps for preparing the T&E are listed in the table below:

T&E

Step

Action

Rotate the elevating hand wheel until approximately 1 1/2

inches are visible on the upper elevation screw.

Rotate the traversing slide until approximately 1 1/2 inches are

visible on the lower elevation screw.

Continued on next page

MCI Course 0321B

3-9

Study Unit 3, Lesson 1

THE M240G MACHINEGUNNER. Maintenance Manual MCI 0321B (2007) - page 1