071-312-4025 (SL1) - Maintain an M249 Machine Gun
Standards: Cleaned and lubricated the M249 machine gun; inspected parts; and turned in unserviceable parts. Assembled the gun and ensured it was operational. Cleaned and inspected linked 5.56-mm ammunition for serviceability. Turned in unserviceable ammunition.

Note. The M249 is available with old and new style barrels. Diagrams used here show the new-style barrel.

1.   Clear the M249 machine gun.

a. Move the safety to the fire position.

b. With your right hand, palm up, pull the cocking handle to the rear and lock the bolt to the rear.

c. Hold the cocking handle to the rear and move the safety to the safe position. Push the cocking handle forward to the locked position. Place weapon on safe.

d. Push the cocking handle forward to its locked position (you should hear a click).

e. Raise the cover and feed mechanism assembly. To check for brass, links, or ammunition—

(1)  Check the feed pawl assembly under the feed cover.

(2)  Check the feed tray assembly.

(3)  Lift the feed tray assembly and inspect the chamber.

(4)  Check the space between the bolt assembly and chamber.

(5)  Insert two fingers in the magazine well and feel for brass or ammunition.

f.  Close the cover and feed mechanism assembly. Move the safety to the fire position.

g. Pull the cocking handle to the rear, press the trigger, and ease the bolt forward.

2.   Disassemble the M249 machine gun.

WARNING: Ensure bolt is in forward position before removing drive spring, return rod, and transfer mechanism assembly

a. Remove the drive spring, return rod, and transfer mechanism assembly.

(1)  Raise the cover assembly. Pull the upper retaining pin at the rear of the receiver to the left. Let the butt pivot downward so the rear opening of the receiver is clear (figure 071-312-4025-1).

Figure 071-312-4025-1. Rear opening of the receiver

Note. The upper and lower retaining pins in the rear of the receiver are captured pins. Do not try to remove them completely during disassembly.

(2)  Hold the weapon with one hand on the buttstock. At the same time, push in and upward on the rear end of return rod and transfer mechanism assembly with thumb of other hand to release it from positioning groove. Withdraw return rod and transfer mechanism assembly and spring (figure 071-312-4025-2).

Figure 071-312-4025-2. Removal of the return rod and transfer mechanism assembly

(3)  Separate the spring from the return rod and transfer mechanism assembly (figure 071-312-4025-3).

Figure 071-312-4025-3. Removal of the spring

b. Remove the operating rod, slide assembly, and bolt assembly.

(1)  Pull the cocking handle to the rear to move operating rod, slide assembly, and bolt assembly out the rear of the receiver (figure 071-312-4025-4).

Figure 071-312-4025-4. Removal of the operating rod, slide assembly, and bolt assembly

(2)  Rotate the bolt clockwise to disengage the lug. Remove the bolt from the slide assembly. Separate the piston from the slide assembly by pressing the rearmost retaining pin to the left and lifting the piston off the slide assembly (figure 071-312-4025-5).

Figure 071-312-4025-5. Removal of the bolt and piston

c. Remove the heat shield. Hold the weapon with one hand. With the other hand, grasp the heat shield just forward of the barrel handle, and lift it off the barrel (figure 071-312-4025-6).

Figure 071-312-4025-6. Removal of the heat shield

d. Remove the barrel (figure 071-312-4025-7).

(1)  Ensure the folding handle on the new style barrel is in carrying (up) position.

(2)  Depress the barrel locking lever with your left hand. Grasp and lift the carrying handle with your right hand. Push the barrel forward.

Figure 071-312-4025-7. Remove the barrel

e. Remove the handguard (figure 071-312-4025-8)

(1)  Push the handguard retaining pin to the left using a section of the cleaning rod.

(2)  Pull downward and remove the handguard.

Figure 071-312-4025-8. Remove the handguard

f.  Remove the gas regulator.

(1)  Position the gas collar so you can insert the scraper assembly into the notch in the front left of the gas block.

(2)  Insert the tip of the scraper assembly in the notch; hold the scraper firmly in position (figure 071-312-4025-9).

Figure 071-312-4025-9. Insertion of the scraper assembly

(3)  Turn the collar counterclockwise and remove it (figure 071-312-4025-10).

(4)  Remove the gas regulator from the gas block (figure 071-312-4025-10).

Figure 071-312-4025-10. Removal of the gas regulator from the gas block

g. Remove the buttstock and buffer assembly.

Note. The upper and lower retaining pins in the rear of the receiver are captured pins. Do not try to remove them completely during disassembly.

(1)  Using a section of the cleaning rod, push the lowermost retaining pin to the left.

(2)  While supporting the trigger mechanism with one hand, use the other to pull the buttstock and buffer assembly rearward and remove it (figure 071-312-4025-11).

Figure 071-312-4025-11. Removal of the buttstock and buffer assembly

h. Remove the trigger mechanism by pulling rearward and down (figure 071-312-4025-12).

Figure 071-312-4025-12. Removal of the trigger mechanism

i.   Remove the gas cylinder.

(1)  Turn the gas cylinder to the left or right to release the locking spring.

(2)  Pull the gas cylinder forward to remove it (figure 071-312-4025-13).

Figure 071-312-4025-13. Removal of the gas cylinder

j.   Remove the bipod. The bipod should slip off the receiver easily. If it does not, turn the bipod left or right to loosen any dirt or corrosion (figure 071-312-4025‑14).

Figure 071-312-4025-14. Removal of the bipod

3.   Clean the M249.

WARNING: Do not use gasoline, kerosene, hydraulic oil, benzene, benzol, high-pressure water, steam, or compressed air for cleaning

Note. Do not use abrasives to clean the bore, piston, gas cylinder, or gas regulator.

a. Clean the bore and chamber using a bore brush, a chamber brush, CLP, and fresh swabs..

b. Clean the gas regulator using the scraper. Do not use CLP on the collar, gas block, or body.

(1)  Clean the gas vent hole (figure 071-312-4025-15).

Figure 071-312-4025-15. Cleaning the gas vent hole

(2)  Clean the central hole of the gas regulator with the appropriate part of the scraper by turning the scraper clockwise and pushing it inward toward the bottom of the housing (figure 071-312-4025-16).

Figure 071-312-4025-16. Cleaning the central hole

(3)  Clean the two grooves of the regulator body using the protruding tips of the scraper (figure 071-312-4025-17).

Figure 071-312-4025-17. Cleaning the grooves of the regulator body

c. Clean the gas cylinder and piston using the scraper. Do not use CLP on the gas cylinder or on the piston.

(1)  Clean the front interior of the gas cylinder (repositioned in receiver with bipod in place) by inserting and turning the flat side of the scraper in a full 360-degree circular motion (figure 071-312-4025-18).

Figure 071-312-4025-18. Cleaning the gas cylinder's front interior

(2)  Clean the internal grooves on the front side of the gas cylinder as previously described (using the protruding tips of the scraper), but insert the scraper farther into the gas cylinder (figure 071-312-4025-19).

Figure 071-312-4025-19. Cleaning the gas cylinder's internal grooves

(3)  Clean the three grooves of the piston using a full, 360-degree circular motion (figure 071-312-4025-20).

Figure 071-312-4025-20. Cleaning the grooves of the piston

(4)  Clean the hole in the front of the piston by inserting and turning the flat side of the scraper in a full 360-degree circular motion (figure 071-312-4025‑21).

Figure 071-312-4025-21. Cleaning the hole in the piston

d. Remove carbon and dirt from all other parts of the weapon using CLP and a wiping rag.

e. Clean ammunition boxes with a brush and clean dry wiping rag.

f.  Clean ammunition with a clean dry wiping rag.

4.   Inspect the M249 machine gun.

a. Inspect the bore and chamber for chips and pitting.

b. Check the front sight for looseness.

c. Inspect the flash suppressor (old style barrel) or compensator (new style barrel), the barrel extension, and the barrel release for cracks, dents, burrs, or other damage.

d. Check the cover assembly for smooth operation, spring tension, bent parts, and excessive wear.

e. Check the cocking assembly for free movement and for bent or cracked parts.

f.  Check the rails for excessive wear, burrs, and chips.

g. Check the barrel locking latch and cover detect springs for spring tension.

h. Check for broken pistol grip and chipped or cracked trigger housing holding lug.

i.   Check the tripping lever and the seat for burrs, cracks, chips, or wear.

j.   Check the cocking action by pushing back on the tripping lever; the sear should rise. Pull the trigger; the sear should lower.

k. Check the safety function. Push the safety to the right (RED BAND NOT VISIBLE). Pull the trigger; the sear will not lower. Push the safety to the left (RED BAND VISIBLE). Pull the trigger again; the sear will lower.

l.   Check the slide assembly, bolt assembly, piston assembly, and return rod and transfer mechanism assembly for burrs, cracks, and broken pins. Push down on roller of slide assembly to ensure it retracts. Check the driving spring for broken strands.

m.   Check bipod legs for correct operation.

n. Check the rear sight assembly for serviceability.

o. Check the ammunition box for damage. Make sure the box latch will engage the receiver dovetail.

p. Inspect ammunition.

(1)  Check for damaged, corroded, or loose bullets.