Final assembly of the rifle

Final assembly of the rifle

You should now have something that looks like this:

Pressing the barrel in

This is the only "mechanical" process in the final assembly. It can be done with a shop press or with the barrel press I outlined earlier.

Shop press

Start by cleaning the inside of the front trunnion and the outside of the chamber end of the barrel. Put some high pressure lube on the inside edge of the front trunnion (I use RCBS case lube.) and start the barrel in by hand. Be sure that the barrel is indexed correctly and is straight and level with the top of the receiver.

Use a 5/8" copper or aluminum rod about 8" long to support the receiver through the mag well with the barrel pointing up. Cushion the muzzle with a penny or nickel to protect it and start pumping the press. The barrel will make some popping sounds as it goes in.

As the barrel gets close to being seated you will need to watch through the barrel pin hole to stop at the proper alignment.

Hand barrel press

Insert the aluminum tube into the muzzle leaving about 1" exposed. Run the thread rod through the aluminum tubing and out the back of the bolt carrier about 1". Run 2 copper washers onto the thread rod and then the tension nut. Thread the key stock block onto the rod at the back of the bolt carrier being sure that the tang on the bolt carrier is in the slot on the block. Lock the block in place with the 1/4" nut.

Hold the rear block in place and run the copper washers up to the muzzle. The aluminum tube will move back on it's own. Place some grease on the muzzle and between the copper washers. Run the tension nut up to the washers and snug it down. Start to tighten the tension nut. Be sure to hold the rear sight block to stop the index from changing. As the barrel gets close to being seated watch through the barrel pin hole to see when it is properly aligned.

Checking headspace

Unless you have a set of headspace gauges I would advise having the headspace checked by a gunsmith.

The first thing to do is strip the bolt and clean the bolt face and the chamber. To strip the bolt you will need to remove the main pin and the extractor pin.

Using a small pin punch driver the main pin out from the bottom and remove the firing pin.

Next, using a small screw driver or punch push the extractor pin out while putting pressure on the extractor face. Remove the extractor and spring. The bolt is now stripped.

Now you will want to completely clean the bolt face and the chamber. Use cleaning solvent and a bore brush to ensure that all residue and grime are removed. The two most common gauges are the "GO" and "NO-GO" and are plainly marked for identification. Be sure that you use gauges made by the same manufacturer to ensure accuracy.

Insert the "GO" gauge into the chamber and close the bolt by hand. The locking lug should seat fully to the top left of the trunnion. Repeat the process with the "NO-GO" gauge. When you seat the bolt on the "NO-GO" gauge use finger pressure only. The bolt should not lock up fully. If you use a lot of pressure you may be able to force it to close. If it closes easily on the gauge then the headspace may need to be reset.

Install the barrel pin

Reinstall the pin is just the opposite of removing it.

Installing a new gas piston

If you have opted to use a US made gas piston as a compliance part it will need to be drilled and riveted in place. Screw the gas piston all the way into the bolt carrier and then back it out 1/2 turn. Use a Sharpie to make a mark through the rivet hole. Unscrew the piston and drill a 1/8" hole through it at the mark.

Insert a rivet and hammer it flat on the anvil of the bench vise. Use the Demel to contour the rivet heads on both sides to match the bolt carrier.

Installing the furniture

Install the pistol grip nut from the inside of the receiver and screw the grip on.

Install the buttstock. It may require some taps with a rubber mallet to seat all the way. Screw the buttstock in place.

Replace the handguard and the gas tube.

Installing the FCG

This section will show the proper installation of the FCG and how it works. First lets look at the parts and how they fit into the receiver.

These are the full auto parts that may have come with your kit. They will not be used in this type of build.

Installing the hammer

The first step is to install the hammer. Insert the hammer into the Hammer/Trigger spring as shown. Secure the long ends of the spring to the hammer with a twist tie.

Turn the hammer sideways and lower it into the receiver. Turn it again so the wings on the hammer are to the back and insert a axis pin from the left. Run the pin all the way through to the matching hole on the right side of the receiver. Secure the pin on the left with tape.

Installing the trigger and disconector

If you are using a captive system assemble as shown.

Drop the assembly into the receiver and insert a axis pin from the left. Run the pin all the way through to the matching hole on the right side of the receiver. Secure the pin on the left with tape.

If you are using a non captive system drop the trigger into the receiver and start the axis pin from the left side but do not put it all the way through. Insert the disconector spring into disconector and lower them onto the trigger. Push the pin the rest of the way through to the matching hole on the right side of the receiver. Secure the pin on the left with tape.

Locking the axis pins

There are 3 basic options for locking the axis pins. The Shepard's hook, a retainer plate or "E" clips.

Shepard's hook

If you received the full auto parts with your kit you should have a long wire with a coil spring on the end. You can use this to make the Shepard's hook by cutting off the spring. The wire then installs over the pins as shown.

Retainer plate

The retainer plate hooks over the hammer pin and rotates down onto the trigger pin. It is held in place by the left side selector arm.

"E" clips

Place one "E" clip on each pin as shown.

Installing the safety selector

Insert the selector from the right side. Make sure that it seats into the matching hole on the left. Rotate the selector forward and down to the selector stop. Remove the twist tie from the hammer and position the spring legs over the rear arms of the trigger.

Holding the trigger back cock the hammer. Be sure that the disconector grabs it and holds it in place. Release the trigger and the hammer should fall forward to the hook on the trigger.

Rotate the safety selector up until the detent is on the top rail. Pull the trigger. The hammer should not release.

If the hammer drops the safety selector will need to have some metal added to the contact arm.

Installing the bolt/carrier and recoil spring

Insert the bolt into the carrier and drop the assembly into the receiver. Run the bolt/carrier assemble forward to the front trunnion.

Insert the recoil spring into the bolt carrier and lock it into the rear trunnion.

Insert the top cover into the slot in the front sight block and push it down into the slot in the rear trunnion until it locks in place.

FINISHED!!!

You should now have something that looks like this.

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