Dissassembly Procedure For Upper Receiver
Bolt Carrier Group
1. Remove the bolt carrier from the weapon by pulling rearward on the charging handle. Set the charging handle aside.
2. Remove the firing pin retaining pin from the bolt carrier.
3. Remove the firing pin from the rear of the bolt carrier.
4. Push the bolt back into its locked position.
5. Turn the cam pin 90 degrees and remove it from the carrier.
6. Remove the bolt from the carrier by pulling forward with a twisting motion.
7. Remove each gas ring (starting with the rear one) by hooking the ring's gap and lifting the end of the ring up and out of the groove. Then spin it off. Be sure not to pull the rings' ends straight apart -- twist them open.
8. Remove the extractor from the bolt by pushing its retaining pin out and lifting off the extractor.
9. Remove the ejector by driving out its retaining pin with a punch and remove the ejector and spring from the front of the bolt.
10. Remove the bolt carrier key (only if necessary.)
1. Remove handguard halves by pulling rearward on the delta ring and pulling outward on the rear of each handguard.
2. Remove the front sight post by depressing the sight detent and unscrewing the sight post. Remove the spring and detent.
3. Remove the compensator/flash suppressor and washer.
4. Remove the front sight base (gas block) by driving out the two tapered retaining pins from left to right.
5. Slide the front sight base and handguard cap off the end of the barrel.
6. Remove the gas tube by driving out its retaining roll pin using a punch.
7. Place the upper receiver in an action block in a vise and remove the barrel nut/delta ring assembly.
8. Separate the weld spring, delta ring, and the barrel nut by removing the snap ring (only if necessary.)
9. Remove the barrel from the upper receiver with a pull and twist motion.
Ejection Port Cover
1. Remove the ejection port cover pin by either pulling forward past the end of the receiver, or if the barrel is in place, remove the "C" clip and pull the pin to the rear.
2. Remove the ejection port cover and spring.
A2 Rear Sight
1. Remove the windage knob by driving out its retaining pin.
2. Remove the windage knob, spring, and ball bearing.
3. Unscrew the rear sight screw and lift out the sight and the leaf spring.
4. Remove the elevation knob pin by driving it out with a punch.
5. Remove the sight base and spring by turning the elevation knob up until the sight base is released. A ball bearing and spring will fall out of the corner of the sight base.
6. Cover the sight with a cloth and remove the elevation knob by pushing it to the left. A ball bearing and spring will pop out of the sight.
A1 Rear Sight
1. Remove the windage drum roll pin with a punch.
2. Remove the windage drum, spring, and detent.
3. Unthread the windage screw.
4. Remove the sight and leaf spring.
1. Remove forward assist assembly roll pin with a punch.
2. Remove forward assist and spring.
3. Further disassembly of the forward assist is not needed unless it is damaged.
Dissassembly Procedure For Lower Receiver
1. Remove the top buttstock screw. Check the breather hole for obstructions.
2. Remove the buttstock, takedown pin's spring and detent, and the receiver extension spacer (A1 will not have spacer.)
3. Remove the swivel screw, rear swivel, and the butt plate if desired.
4. Cock the hammer, depress the buffer retainer, and pull the buffer and its spring forward out of the receiver extension.
5. Remove receiver extension (buffer tube) with a wrench, while holding the buffer retainer in place.
6. Remove buffer retainer and spring.
1. Cock the hammer, depress the buffer retainer, and pull the buffer and its spring forward out of the receiver extension.
2. Remove the buttstock from the receiver extension (buffer tube) by pulling straight down on the latch and pulling rearward.
3. Loosen the castle nut with spanner wrench.
4. Remove the takedown pin's spring and detent.
5. Remove the receiver extension while holding the buffer retainer in place.
6. Remove buffer retainer and spring.
Lower Parts Set
1. Remove the rear takedown pin.
2. Remove pistol grip screw, pistol grip, selector spring, and detent.
3. Release tension on the hammer pin by pulling the trigger rearward and lowering the hammer slowly. Do NOT let the hammer fall under its own power, as this may cause damage.
4. Remove the hammer pin with a 1/8" punch.
5. Remove the hammer and its spring.
6. Remove the selector lever.
7. Remove the trigger pin with a 1/8" punch.
8. Remove the trigger and its spring, and the disconnector and its spring.
9. Remove the bolt catch pin with a punch. Place tape on the lower receiver on either side to avoid scratches.
10. Remove the bolt catch, spring, and plunger.
11. Remove the magazine catch by depressing the mag catch button with a punch and turning the catch itself counter-clockwise until it is unscrewed.
12. Remove the front pivot pin by pulling it into its open position. Take a razor blade and slide it between the detent and pivot pin, and slide the pivot pin out of the lower receiver. Take special care when removing the razor blade, as the spring and detent are under pressure.
13. Remove the trigger guard by driving out its roll pin with a 1/16" punch (only if necesary.)
Assembly Procedure Of Upper Receiver
1. Insert the forward assist assembly and spring into the upper receiver.
2. Press the forward assist assembly into the upper receiver until the notch for the roll pin is aligned with the roll pin's hole.
3. Drive forward assist roll pin into place.
A2 Rear Sight
1. Insert spring and ball bearing for rear elevation knob. You can use a dab of moly grease to hold the ball bearing into place.
2. Remove the index screw from the elevation knob with a 1/16" hex wrench.
3. Using a punch, hold down the spring and detent and insert the elevation knob into the upper receiver.
4. Insert the spring and ball bearing into the corner of the rear sight housing and engage the threads into the elevation knob.
5. Turn elevation knob until the sight base is fully seated.
6. Start the elevation spring retaining pin into the receiver.
7. Insert the elevation spring under the receiver. Hold it in place with a punch (or the special tool made just for this purpose), then drive the retaining pin completely into the upper receiver.
8. Confirm elevation knob has been bottomed on the sight base.
9. Turn the index wheel until the "8/3" is lined up with the mark on the upper reciver.
10. Insert the index screw through the elevation knob and tighten.
11. Insert the leaf spring.
12. Thread the rear sight screw into the housing.
13. Hold the spring and detent into the windage knob and press it onto the rear sight screw.
14. Drive the retaining pin through the windage knob.
A1 Rear Sight
1. Replace leaf spring and rear sight.
2. Thread in windage screw.
3. Install windage drum and roll pin.
Ejection Port Cover
1. Replace the ejection port cover.
2. Push the rod halfway through the ejection port cover and spring.
3. Gently bend the open end of the spring up towards you, give it a twist to preload it, then press it back flat into place.
4. Push the ejection port cover pin the rest of the way through and install the "C" clip.
1. Put some moly lube on the barrel extension and insert the barrel into the upper receiver (which should be in an action block and vise), aligning the index pin of the barrel with the slot in the upper receiver.
2. Reassemble the barrel nut assembly if needed. Coat the barrel nut's threads with moly grease and thread it onto the receiver.
3. Torque the barrel nut to 30 ft. lbs. using an armorer's wrench and torque wrench. Apply additional torque (if necessary) to the barrel nut to provide adequate clearance for the gas tube to move through the barrel nut assembly.
4. Insert the gas tube into the front sight base assembly and pin it in place with the gas tube roll pin.
5. Slide the front sight base assembly over the barrel and align the gas tube with the hole in the front of the upper receiver (and delta ring assembly) and push it into place.
6. Pin the front sight base into place with the two tapered pins (from right to left.)
7. Apply anti-seize to the barrel's threads and replace the flash suppressor peel/crush washer and flash suppressor.
8. Align the flash suppressor slots with approximately 25 ft. lbs. torque.
9. Install the front sight spring and detent.
10. Screw in the front sight post.
11. Install handguards by pulling rearward on the delta ring, placing the front of each handguard into the front cap and pushing inward on the rear of each handguard.
1. Replace the bolt carrier key (if removed) using red Loc-Tite as a gasket and torque the hex screws to 35-40 inch lbs. and stake them in place.
2. Install the gas rings onto the bolt by winding them on from the rear of the bolt. Offset the gaps in the rings.
3. Install ejector spring and ejector and pin in place.
4. Install extractor with spring and pin into place.
5. Replace bolt into bolt carrier with a twisting motion. Align the cam pin hole in the bolt with the hole in the bolt carrier.
6. Install the cam pin and rotate it 90 degrees.
7. Pull the bolt forward to its unlocked position.
8. Install the firing pin and firing pin retaining pin.
9. Check firing pin protrusion with gauge. With a firing pin protrusion gauge, check for proper protrusion by pushing the firing pin forward in the bolt. Place the gauge end marked "Max" over the firing pin -- it should pass over the firing pin without touching. Turn the gauge and pass the "Min" over the pin -- it should hit the pin and not pass over.
Assembly Procedure For Lower Receiver
Lower Parts Set
1. Take a small drill bit and clean out all holes in the lower receiver BY HAND.
2. Install trigger guard by attaching its front into the lower receiver using the detent. Using a block of wood as a support, hinge the trigger guard into place, and drive the rear roll pin into place with a 1/8" roll pin punch. Use extreme caution or you may break off one of the flanges.
3. Install front pivot pin by placing its spring and detent into the lower receiver. Compress detent in hole with special tool and punch, or with a razor blade. Install pivot pin and rotate it until detent locks in the pivot pin's groove.
4. Install magazine catch into the lower receiver. Install its spring and screw the button on a few turns. Use something to depress the button deeply and turn the magazine catch clockwise until the end of the threaded portion is flush with the button.
5. Install the bolt catch assembly by first placing tape on either side of the "humps" to prevent scratches. Drive the roll pin about halfway into the rear "hump". Install the spring and plunger into the hole, then install the bolt catch in place. Use a 3/32" punch inserted into the front "hump" as a slave pin to hold everything in place, and drive the roll pin in with a 3/32" roll pin punch.
6. Place trigger spring on trigger with legs of spring forward and on bottom. Install disconnector spring (wide end down) into top of trigger and snap it into place. Position disconnector on top of trigger, and insert entire assembly into the lower receiver. Drive trigger pin through both sides of the lower receiver and trigger assembly.
7. Install selector.
8. Install hammer spring onto hammer with legs at bottom rear and the spring's shoulder on back of hammer. Install hammer with spring's legs ON TOP of trigger pin, with one leg in the trigger pin's groove. Insert the ungrooved end of the hammer pin into the lower receiver and hammer, and drive it into place.
9. Install the selector's detent and spring into the lower receiver, then install the pistol grip. Make sure that the spring goes into the small hole on the top right side of the pistol grip, and tighten the pistol grip's screw.
10. Install the rear takedown pin into the lower receiver.
1. Thread the castle nut all the way onto the buffer tube, then install the back plate (hump forward) in front of it.
2. Install the rear takedown pin's detent and spring into their hole in the lower receiver.
3. Thread the receiver extension (buffer tube) into the lower receiver about 3/4 of the way.
4. Insert the buffer retainer and its spring into the lower receiver.
5. Tighten the receiver extension until it overlaps the buffer retainer to hold it in place.
6. Tighten the castle nut with a spanner wrench, while making sure that the takedown pin's spring gets compressed into its hole correctly by the back plate.
7. Slide the buttstock onto the receiver extension by pulling straight down on the latch.
8. Cock the hammer and slide the spring and buffer into the receiver extension while depressing the buffer retainer.
1. Thread the receiver extension (buffer tube) into the lower receiver about 3/4 of the way.
2. Insert the buffer retainer and its spring into the lower receiver.
3. Tighten the receiver extension (which will overlap the buffer retainer), and torque to 35-39 ft. lbs.
4. Install the rear takedown pin's detent and spring into their hole in the lower receiver.
5. Add spacer (not necessary on A1), then slide buttstock onto receiver extension, while carefully compressing the takedown pin's spring.
6. Tighten the buttstocks top screw.
7. Cock the hammer and slide the spring and buffer into the receiver extension while depressing the buffer retainer.
Function Checking The Rifle
1. Pull the charging handle to cock the hammer.
2. Pull the trigger -- the hammer should fall.
3. Without releasing the trigger, pull the charging handle back again to cock the hammer. The hammer should be caught by the disconnector.
4. Release the trigger -- the hammer should NOT fall. It should be caught by the trigger.
5. Hammer should fall when trigger is pulled now.
I hope that some of you new guys printed these instructions out for future reference.
I'm not much of a typist, and it took me quite a while to type all of this out.
Thanks for putting in the time M4Madness!!
Awesome post!! Thanks a lot. This will be very helpful to all us newbies.
A+ for effort, but why not simply point the new guys towards our page with .PDF versions of the manuals?
I figure that as many times as certain questions get asked (and as lazy as I am when it comes to retyping the same thing over and over ) that this format makes it easier for me to copy and paste answers into future threads.