Disassembly of Bolt Carrier and AssemblyUpdated June 19th, 2015
- Remove firing pin retaining pin
- Tip key and bolt carrier assembly and catch firing pin as it drops out.
- Rotate bolt cam pin one quarter turn and lift straight up to remove.
- Remove bolt assembly from key and bolt carrier assembly
Clean carrier key and gas relief ports.
- Inspect bolt assembly to verify that gaps in bolt rings are staggered and approximately 1/3 turn apart.
- Inspect firing pin retaining pin and bolt cam pin for cracks, damage, or excessive wear. Replace if unserviceable.
- Inspect key and bolt carrier assembly for burrs, cracks, wear, and evidence of gas loss. Replace if unserviceable.
- Inspect carrier key for dents, damage, or looseness. If dented, or loose, repair or replace.
- Visually inspect the carrier keys for looseness and proper staking.
- Inspect tip of firing pin for proper contour. Inspect for pitting, wear and burrs.
- Check for binding in the bolt assembly. Before reassembly exercise the bolt assembly in and out to check for binding.
- Check bolt assembly for proper fit with cam pin removed. Turn bolt carrier assembly so that the bolt is pointed downward. The bolt assembly must not drop out. If weight of bolt assembly allows it to drop out, replace bolt rings.
Assembly of Bolt and Bolt Carrier Assembly
- Lubricate parts in the assembly.
- Install bolt assembly into key and bolt carrier assembly.
- Hold key and bolt carrier assembly with bolt assembly down and drop in firing pin.
- Install firing pin retaining pin from left side only to ensure proper installation. Check installation by trying to shake firing pin out.
Bolt Assembly Disassembly
- Push out extractor pin and remove cartridge extractor and extractor spring assembly as a unit.
- Remove the ejector. Hold the bolt in vise and remove spring pin using 1/16 punch and hammer. Remove punch, being sure to catch cartridge ejector and ejector spring.
Inspection of Bolt
- Inspect bolt for pitts, burrs and wear. If bolt appears to be damaged it is recommended to be replaced.
- Inspect bolt for cracks in both the locking lugs and cam pin hole area.
- Check gas rings for cracks, kinks, bends or improper staggering. They should be equally spaced.
- Inspect extractor, extractor spring assembly and extractor pin for cracks breaks or other damage.
- Inspect cartridge ejector and ejector spring for cracks breaks and chips.
- Carefully place one end in the bolt ring groove and hold in place with thumb of one hand. Gently guide the rest of the gas ring into the groove a little bit at a time until the bolt ring is in place. Make sure the gaps are staggered.
- Install three gas rings, one at a time using care not to bend or spring new bolt rings.
- Place bolt in vise and start spring in hole.
- Install ejector spring and cartridge ejector. Align groove on cartridge ejector so that the spring pin can be installed.
- Compress and hold ejector spring and cartridge ejector in place with a 3/8 in punch.
- Using a hammer and a 1/16 in punch complete the installation of roll pin so that the ends are flush with the outside of the bolt.
- If removed insert large end of extractor spring assembly into cartridge extractor and seat by pushing and turning clockwise.
- Position cartridge extractor and extractor spring assembly on bolt.
- Compress extractor spring assembly and cartridge extractor to align holes.
- Install extractor pin by hand.
Bolt Carrier Disassembly
- Using a socket wrench with a 1/8 in socket head screw attachment remove two carrier key screws and discard the screws.
- Remove gas key from bolt carrier.
Repair or replacement
- If disassembled, place bolt carrier in vise using vise jaws. Install and position bolt carrier key on carrier.
- Install two new carrier key screws.
- Using a 1/8 in socket head screw attachment and an inch pound torque wrench torque the carrier key screws to 50-58 in lb. or 5.65 to 6.55 newton meters.
- Use a solid center punch and a hammer to stake the carrier key in three places.
- Reassemble the firearm
- If the key is replaced, expect to have to manually fire up to 10 rounds before the rifle starts functioning normally.
Charging Handle Disassembly
- Remove roll pin from charging handle using a hammer and a 1/16 in. punch.
- As punch is being removed take caution to catch the charging handle latch and spring to prevent loss.
- Lightly lubricate all items
- Position spring and latch into handle so that holes in the charging handle and latch line up
- Install roll pin using hammer being sure the roll pin is flush.
Lower Receiver Disassembly
- Remove screw and lock washer from pistol grip.
- Carefully remove pistol grip, spring and safety detent.
- Remove stock according to which you have.
- For a fixed stock, remove the screw at the end of the stock, slide the stock off of the receiver extension.
- For a carbine stock, extend the butt stock assembly, grasp the lock lever in the area of the retaining nut and pull downward. While pulling downward slide the butt stock assembly to the rear to separate from the lower receiver.
- Extend the pivot pin until it locks, take a paperclip or other thin object and place it through the hole in the pivot pin to press the pivot pin detent. Rotate the pin so that the groove in the pin is not facing the detent. Cup your hand around the pivot pin area and catch the spring and detent while removing the pivot pin.
- Make sure the hammer is in the cocked position before attempting to remove the buffer assembly. Press buffer assembly in about ¼ of an inch. Depress buffer retainer and release buffer assembly and action spring. Remove buffer assembly and action spring from receiver while depressing buffer retainer.
- Removal of magazine catch. Using a punch press the magazine button in until you can unscrew the magazine catch counter clockwise until it separates from the magazine button. Remove magazine catch button and magazine catch spring.
- Removal of hammer assembly. Use a punch to drive the hammer pin from the lower receiver, then remove hammer assembly.
- Removal of trigger assembly. Remove the trigger pin by pushing from the left side of the lower receiver and receiver extension assembly with a punch or a slave pin. Remove disconnector and trigger assembly. Be sure not to lose the disconnector assembly.
Assembly of Lower Receiver
- Clean and remove carbon deposits from all items, lightly lubricate all metal components.
- If you have a slave pin, assemble the disconnector into the trigger using the slave pin to retain it. Insert the trigger assembly into the lower receiver, install trigger pin using trigger pin and a punch. Push in until flush. The slave pin will fall out.
- Install hammer assembly, install hammer pin using a punch. Push in until flush. Ends of hammer spring are installed to the rear of the trigger pin, resting in the groove on the trigger pin.
- Hammer assembly must be cocked prior to installation of the selector lever. Install selector lever.
- Install magazine catch. Push on magazine catch button using drive pin punch and turn magazine catch clockwise until threaded end of magazine catch is flush with head of magazine catch button.
- Make sure hammer is cocked prior to installation of buffer assembly. Insert action spring and buffer until buffer retainer snaps up and holds them in place.
- Using a ¼ punch insert it through the opposite side of the pivot pin detent. Insert the pivot pin spring and pivot pin detent and press them into the pivot pin detent hole. Slide the punch over the hole to keep the pivot pin detent depressed. Insert the pivot pin from the pivot pin detent side and push in. Rotate pivot pin until the detent snaps into place.
- Depending on which stock you have assembly will vary.
- Rifle stock. Do not king spring during assembly. Install stepped spacer on the lower receiver extension assembly and carefully slide buttstock assembly into position to compress spring. Install a new machine screw to secure the buttstock.
- Carbine stock. Pull down the lock release lever in the area of the retaining nut and reinstall buttstock assembly onto lower receiver and receiver extension assembly.
- Install safety detent, pointed end first and spring into bottom of lower receiver and receiver extension assembly.
- Carefully install pistol grip to compress spring, secure pistol grip in place with a new lock washer and machine screw.