M4/M16 DISASSEMBLY & FUNCTIONS CHECK
Conditions: You have just returned from a mission and have been directed to conduct maintenance on your carbine/rifle. Performed AFTER the 12-mile foot march.
Understanding This Task
This is the last event of ESB testing, performed immediately after the 12-mile foot march (no more than 5 minutes rest). Your hands will be shaking, your fine motor skills degraded. This task is identical to W1 Part I maintenance, but with tighter time standards.
NOT re-testable. If you fail this event, you are eliminated. There are no second chances.
Functions check sequence: SAFE (no fire) > SEMI (fires) > hold trigger, charge, release trigger (click) > pull trigger (fires) > BURST/AUTO as applicable.
Common NO-GO Mistakes
- This event is NOT re-testable — fail and you're done
- Performed after 12 miles — fatigue causes fumbling and lost time
- Wrong functions check sequence (SAFE > SEMI > trigger reset > BURST/AUTO)
- Not separating bolt, firing pin, bolt cam, and firing pin retaining pin
- Exceeding 2:30 for either phase
Starting Configuration
Weapon: Free of ammunition, loaded with empty magazine, bolt forward, on SAFE, with sling.
Note: No more than 5-minute rest period between foot march completion and this event.
Task Basis: 130-CLC-0029
- Performed AFTER all other testing and the 12-mile foot march — fatigue is real.
- This event is NOT re-testable — fail and you're done.
- Functions check: SAFE (no fire) > SEMI (fires) > BURST/AUTO as applicable.
- No more than 5-minute rest between foot march and this event.
PERFORMANCE MEASURES
0/4 GO-
1
Clear the weapon
- Point weapon in safe direction. Ensure on SAFE.
- Remove magazine.
- Lock bolt open — pull charging handle rearward, press bottom of bolt catch.
- Return charging handle to forward position.
- Ensure receiver and chamber are free of ammunition.
- Press upper portion of bolt catch to allow bolt forward.
-
2
Disassemble the weapon into 5 groups
- Lower receiver and upper receiver — separated but connected by sling.
- Charging handle and bolt carrier — separated from each other.
- Bolt, firing pin, bolt cam, and firing pin retaining pin — all separated.
- Buffer and buffer spring — separated.
Time stops when you return to standing with all parts on flat surface.
-
3
Assemble the weapon
- Reassemble in reverse order. Ensure all components properly seated.
-
4
Perform a functions check CRITICAL
- Place selector on SAFE. Charge weapon (pull charging handle, release).
- Pull trigger — hammer should NOT fall.
- Place selector on SEMI. Pull trigger — hammer SHOULD fall.
- Hold trigger to rear. Charge weapon (pull handle, release).
- Release trigger slowly — audible click should be heard (trigger reset).
- Pull trigger — hammer SHOULD fall.
- For BURST: Place on BURST. Charge and squeeze trigger (hammer falls). Hold trigger, charge weapon 3 times. Release trigger and squeeze — hammer should fall.
- For AUTO: Place on AUTO. Charge and squeeze trigger (hammer falls). Hold trigger to rear, cock weapon again. Release trigger and squeeze — hammer should NOT fall.
- Charge weapon, place on SAFE, close dust cover.
Time stops when you return to standing with weapon on flat surface.