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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
As the barrel gets close to being seated you will need to watch through the barrel pin hole to stop at
Hand barrel 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. Using something to pad the receiver, lock it
into the bench vise. Install the bolt carrier all the way forward.
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.
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
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
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
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
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
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
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
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
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
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
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
FINISHED!!!
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CYA message: This web page is posted for informational and educational use only. Any other use of the information on this website is solely at the user's risk.