Weapons Lane
W3

M240B MACHINE GUN

3 min (disassemble) 3 min (assemble + functions check) 30 sec (operate)

Conditions: Part I: You have been directed to conduct maintenance on your M240 machine gun. Part II: You have a stoppage while engaging targets.

Understanding This Task

The M240B is the platoon-level medium machine gun, firing 7.62mm ammunition. Like the M249, this task has two parts: maintenance (disassemble/reassemble) and operate (load/fire/immediate action).

Four-Point Safety Check: The M240B uses a four-point check — feed pawl, feed tray, chamber, and bolt face. There is no magazine well to check (unlike the M249).

Key difference: After the functions check, the safety must NOT be able to move to SAFE — this confirms the firing pin is forward, which is the correct resting state.

Common NO-GO Mistakes

  • Performing a five-point check instead of four (no magazine well on M240)
  • After functions check: safety SHOULD NOT engage — if it does, weapon is not properly assembled
  • Not ensuring safety on FIRE before moving bolt/operating rod
  • Right hand NOT palm up when pulling cocking handle
  • Placing parts on wrong nomenclature labels

Starting Configuration

Weapon: Free of ammunition, on FIRE, bolt forward. Bipod legs extended on flat surface.

Part I: Standing position, weapon on flat surface. Nomenclature labels provided.

Part II: Prone position, not touching weapon. Blank ammo belt with one dummy round in middle.

Task Basis: 071-025-0001, 071-025-0002, 071-025-0003, 071-025-0005, 071-025-0004

Video Resources

ESB 2022: M240B — 1-2 SBCT
SSG Joyce demonstrates M240B operating procedures for ESB
Know Your Tasks: M240B Machine Gun
SGM Robinson demonstrates all ESB M240B tasks
Part I Disassemble Timer: 3 Minutes
3:00
Critical Notes
  • Four-point safety check (NO magazine well — unlike M249).
  • After functions check, safety must NOT engage — this is a graded step.
  • Always right hand PALM UP on cocking handle.

PART I: MAINTAIN (DISASSEMBLE / ASSEMBLE)

0/4 GO
  1. 1

    Clear the weapon

    • Point weapon in safe direction. Ensure safety on FIRE before moving bolt/operating rod assembly.
    • Pull and hold cocking handle with right hand palm up to rear, bolt locks to rear.
    • While holding (no tension on bolt), place safety to SAFE.
    • Release cocking handle to fully forward and locked position.
    • Raise feed cover — conduct four-point safety check: feed pawl assembly under cover, feed tray, lift feed tray and inspect chamber, check between bolt face and chamber and under bolt/operating rod assembly.
    • Lower feed tray and close feed cover (locks shut).
    • Pull cocking handle to rear (palm up). Place safety to FIRE.
    • While fully depressing trigger, ease bolt forward to close and lock. Release trigger.
    • Attempt to place safety to SAFE — safety must NOT be able to move to SAFE.
  2. 2

    Disassemble the weapon into groups

    • Buttstock and buffer assembly
    • Bolt and operating rod assembly
    • Driving spring rod assembly
    • Trigger housing assembly
    • Barrel assembly (removing heat shield)
    • Cover assembly
    • Feed tray
    • Receiver assembly

    All parts on correct nomenclature labels. Time stops when you return to standing.

  3. 3

    Assemble the weapon

    • Reassemble in reverse order of disassembly.
  4. 4

    Perform a functions check CRITICAL

    • Ensure safety on FIRE before moving bolt/operating rod assembly.
    • Pull and hold cocking handle (palm up) to rear — bolt locks to rear.
    • Place on SAFE, depress trigger — weapon should NOT fire.
    • Place on FIRE, depress trigger. Ease bolt forward to close and lock. Release trigger.
    • Attempt to place on SAFE — safety must NOT be able to move to SAFE. Close ejection port cover.

    Time stops when you return to standing with weapon on flat surface.

PART II: OPERATE (LOAD / FIRE / IMMEDIATE ACTION)

Part II Timer: 30 Seconds
0:30

PERFORMANCE MEASURES

0/5 GO
  1. 1

    Clear the weapon

    • Point weapon safe direction. Ensure safety on FIRE before moving bolt.
    • Pull and hold cocking handle (palm up) to rear, bolt locks to rear.
    • While holding (no tension), place safety to SAFE.
    • Push cocking handle fully forward and locked.
    • Raise feed cover — conduct four-point safety check. Check feed pawl, feed tray, chamber, bolt face.
    • Lower feed tray.
  2. 2

    Load the weapon

    • Place link belt on feed tray — first round against cartridge stop, tips pointing toward barrel.
    • Tilt weapon right and/or hold belt in place if necessary.
    • Close feed cover, ensuring latches lock. Rounds must not move from cartridge stop.
  3. 3

    Engage the target

    • Place weapon on FIRE and engage your target.
  4. 4

    Take immediate action to correct malfunction CRITICAL

    • Weapon remains on shoulder during immediate action.
    • Pull and hold cocking handle (palm up) to rear — bolt locks to rear.
    • Observe ejection port: see if cartridge case/belt link/round ejects.
    • If nothing ejects: Place on SAFE (no tension on bolt). Return handle forward and locked. Proceed to clear.
    • If something ejects: Push cocking handle forward. Squeeze trigger and continue mission.
  5. 5

    Unload and clear the weapon

    • Point weapon safe direction. If bolt forward: ensure safety on FIRE. If bolt locked to rear: ensure on SAFE, proceed to feed cover.
    • Pull and hold cocking handle (palm up) to rear. Place safety to SAFE.
    • Return cocking handle fully forward and locked.
    • Raise feed cover — four-point safety check. Lower feed tray, close feed cover.
    • Pull cocking handle to rear (palm up). Place safety to FIRE.
    • While depressing trigger, ease bolt forward. Release trigger. Close ejection port cover.
W2: M249 SAW W4: M2 .50 Cal