Reasons to
Change Barrels Change barrels periodically during firing. Use one barrel while the other is cooling. Changing barrels
· Increases the life of each barrel.
· Ensures a continuous rate of accurate fire.
When to Change the Barrel
Change the barrel if
· You fire the sustained rate of fire for 10 minutes (1,000 rounds in 10 minutes).
· You fire the rapid rate of fire for 2 minutes (400 rounds in 2 minutes). · The barrel becomes so hot that handling it is difficult.
· You have fired a long burst of continuous fire.
Note: The barrel can be changed with the bolt forward or to the rear.
After Firing The following table lists the maintenance steps to take after firing the M240G.
Step Action
1 Clean the weapon with CLP, RBC, or dry cleaning solvent.
2 Clean the weapon for three consecutive days after firing to remove all carbon deposits.
3 After the cleaning each day, wipe off all cleaning materials and place a light coat of CLP on all metal parts. 4 Clean nonmetallic portions of the gun with hot water, rags and
nonabrasive brush.
Maintaining,
ContinuedGeneral Maintenance Notes
If the weapon is fired daily, repeated detailed disassembly will cause
unnecessary wear. You can perform adequate cleaning on a weapon that has been disassembled into the five main groups.
Clean the M122 tripod and T & E mechanism on the same three consecutive days cleaning cycle as the machinegun.
CAUTION: Do not use cleaning materials on the rubber parts of the weapon. Do not submerge the buffer in any cleaning fluid.
Normal
Maintenance Inspect the weapon daily for rust. Maintain a light coat of CLP on all metal parts except
· The gas piston
· Inside of the gas cylinder · The buffer
MCI Course 8017A 4-38 Study Unit 4, Lesson 3
Maintaining,
ContinuedExtreme
Environments In extreme environments, you must take extra precautions for the trouble-free operation of your M240G. The following table shows the precautions you
must take in these conditions.
Environment Precautions
Cold climates · Keep the weapon free of excess lubricants, cleaners, and moisture. All of these can freeze and cause the weapon to operate sluggishly. · Use LAW in sustained temperatures of 0o
Fahrenheit or below.
· If you bring the weapon indoors, let it come to room temperature, wipe it completely dry, and lubricate with a light coat of CLP.
Hot, humid climates · Inspect more frequently for rust and keep the weapon as free from moisture as possible. · Lubricate the weapon properly with CLP.
Generally, a heavier application than normal is required.
Hot, dry climates · Keep sand and dust from collecting in the working parts of the weapon.
· Clean the weapon daily with CLP, then wipe dry. The Teflon coating left by the CLP will be
sufficient for the weapon to operate properly. · Cover the weapon when not in use.
Assembling
Sequence The sequence for assembling the M240G is the reverse order of fieldstripping. · Assemble and replace the operating group
· Replace the receiver group · Replace the buttstock
· Replace the trigger housing group · Replace the barrel
Assembling the Operating Group
The following table lists the steps to assemble and insert the operating group.
Step Action
1 Insert the bolt and operating group into the receiver, aligning the slots with the rails inside the receiver as shown in the figure below.
2 Extend the bolt forward and then push the entire bolt and operating rod assembly inside the receiver.
MCI Course 8017A 4-40 Study Unit 4, Lesson 3
Assembling,
Continued Assembling the Operating Group, continued Step Action3 Insert the drive spring rod into the receiver.
4 Press in and down until the spring rod is seated against the retaining studs inside the receiver as shown in the figure below.
Replacing the
Buttstock The following table lists the steps to replace the buttstock.
Step Action
1 Depress the buttstock release latch.
2 Align the recessed grooves at the front of the buttstock with the vertical rails at the rear of the receiver and slide down until it locks in place as shown in the figure below.
Assembling,
ContinuedReplacing the Trigger
Housing Group
The following table lists the steps to replace the trigger housing group.
Step Action
1 Insert the holding notch on the front of the trigger housing into the recess on the bottom of the receiver.
2 Insert the trigger housing group in and up as shown in the figure below.
3 Replace the spring pin.
MCI Course 8017A 4-42 Study Unit 4, Lesson 3
Assembling,
ContinuedReplace the
Barrel The following table lists the steps to replace the barrel.
Step Action
1 Insert the gas plug into the gas regulator.
2 Place and rotate the collar over the forward end of the plug and lock in place.
3 Depress and hold the barrel locking latch.
4 Insert the barrel with the handle in the upright position as shown in the figure below.
5 Rotate the barrel to the right until is locks.
Note: There must be a minimum of two clicks, but mot more then seven.
Assembling,
ContinuedReplace Feed
Tray and Cover The following table lists the steps to replace the feed tray and cover assembly. Step Action
1 Align the feed tray guides with receiver brackets.
2 Place the cover over mounting bracket on receiver and push down into closed position as shown in the picture below.
MCI Course 8017A 4-44 Study Unit 4, Lesson 3
Inspecting
Guidelines General guidelines for inspecting the M240G are to · Always check for cleanliness
· Look for broken, missing, or burred parts · Test springs for serviceability
· Perform a function check to determine if the weapon is functioning properly
· Inspect the M240G in an orderly sequence to be sure that no part is overlooked and time isn't wasted
Sequence The following table lists the suggested sequence for inspecting the M240G.
Step Action
1 Inspect the cover:
· Pull the feed cam back and forth to be sure that the belt feed pawl moves properly.
· Carefully check parts and components for serviceability and proper function.
2 Inspect the safety and proper assembly by performing a function check as described in the table below.
Step Action
1 Put the safety on F.
2 Pull and ensure the bolt locks to the rear. 3 Return the safety to S and attempt to fire.
4 Put the safety on F and pull the trigger riding bolt home.
Note: If the bolt did not remain to the rear, the sear shoulder or sear notch is worn.
3 Inspect the forward portion of the receiver rails and the face of the bolt.
4 Inspect the barrel socket, chamber, and bore for cracks. 5 Inspect the bipod assembly by lowering and raising the legs. 6 Inspect the sights.