110831-N-BT887-041 (by U.S. Pacific Fleet)

PACIFIC OCEAN (August 31, 2011) Aviation Ordnanceman Airman Scott Segel, from Antioch, Ill., changes the barrel of a .50 caliber machine gun aboard the Nimitz-class aircraft carrier USS John C. Stennis (CVN 74). John C. Stennis Carrier Strike Group is on a scheduled Western Pacific Ocean and Arabian Gulf deployment. (U.S. Navy photo by Mass Communication Specialist 3rd Class Benjamin Crossley/Released)

HEAD SPACE AND TIMING PROCEDURE

1. PULL CHARGING HANDLE FULLY TO THE REAR AND VERIFY NO ROUND IN FEEDWAY OR CHAMBER.

2. PERFORM HEADSPACE CHECK BY FIRST INSERTING THE GO THEN NO GO GARGE INTO THE T-SLOT GAUGE SHOULD ENTER T-SLOT TO CENTER RING.

3. REMOVE GO END OF GAUGE AND INSERT NO GO GAUGE. IF IT DOES NOT ENTER, HEADSPACE IS CORRECT. REMOVE HEADSPACE TOOL.

4. IF HEADSPACE IS INCORRECT ROTATE BARREL CW OR CCW. DO NOT EXCEED 2 CLICK MIN AND 7 CLICK MAX BARREL POSITION CW, CCW IS VIEWED FROM MUZZLE END.

5. IF HEADSPACE IS INCORRECT RETRACT RECOILING PARTS UNTIL LUGS ON BARREL ARE VISIBLE.

6. IF GO GARGE WON’T GO ROTATE CCW 1 NOTCH. RE-CHECK HEADSPACE. REPEAT UNTIL HEADSPACE IS CORRECT.

7. IF NO GO GAUGE GOES REPEAT STEP 4 ROTATING BARREL CW 1 NOTCH. RE-CHECK HEADSPACE. REPEAT UNTIL CORRECT.

TIMING PROCEDURE

ENSURE HEADSPACE IS CORRECT

ENSURE FIRING PIN IS COCKED, BOLT IS FORWARD,

AND CHAMBER IS NOT LOADED.

RAISE EXTRACTOR.

RETRACT RECOILING PARTS SUFFICIENTLY TO INSERT NO FIRE

GAUGE BETWEEN BARREL EXTENSION AND TRUNION BLOCK.

ALLOW BARREL TO SLOWLY CLOSE ON GAUGE.

PLACE SAFETY TO FIRE AND DEPRESS TRIGGER FULLY IF FIRING PIN.

IF PIN FALLS, TIMING IS EARLY AND GUN REQUIRES MAINTENANCE.

REMOVE GAUGE.

RETRACT RECOILING PARTS FAR ENOUGH TO INSERT FIRE TIMING

GAUGE. SLOWLY LET BOLT FORWARD.

8. PLACE SAFETY TO FIRE AND DEPRESS TRIGGER FULLY IS FIRING PIN

FALLS TIMING IS GOOD IF FIRE PIN FAILS TO FALL TIMING IS LATE.

REMOVE TIMING GAUGE IF TIMING IS OFF GUN REQUIRES

MAINTENANCE