Preparing the parts kit
When you receive your parts kit it will look something like this:
Removing the furniture
It will be necessary to remove the receiver stubs and old rivets as well as press the barrel out. You will want to start by removing the furniture. On the right side of the rear sight block is a lever that needs to be rotated back and up to release the gas tube. Once it is in the open position you can lift the gas tube up and back to remove it.
Next you will remove the handguard. At the front of the handguard is the retainer. There is a lever on the right inside that needs to be rotated forward 180 degrees. Once this is done you can move the retainer forward and pull the handguard down from the front and off.
Next you will remove the buttstock from the rear trunnion. Start by removing the 2 screws from the top. Once they are out lock the trunnion in the bench vise and use a ram to tap the buttstock out.
Removing the barrel pin
The next step is to remove the barrel pin. In most cases this can be done by locking the front trunnion in the vise and using a punch to tap it out. You can also use a shop press and barrel pin punch adapter.
Hammer and punch
You want to start with a punch that is larger than the pin to get it to move. It will require several solid blows with the hammer to do this. It is best to hold the punch with the vise grips to avoid damage to your hand. Once the pin has started to move you will finish tapping it out with a .250" punch.
Shop press
Install the pin punch adapter to the ram on the press. Place the trunnion on a piece of hard wood (Oak works well) with a 3/8" hole through it. Center the pin over the hole and and start pressing it out with the short pin. Once it starts to move use the longer pin to finish pressing it out.
Pressing out the barrel
Next you will press the barrel out of the front trunnion. There are several ways to do this depending on what tools you have access to:
Gear puller
You can buy a gear puller from most auto parts stores for less that $20. You may need to modify the front arms to fit over the trunnion. Once the trunnion is located in the puller lock it in the vise. I use the "C" clamp to keep the puller stable. Using a piece of 5/8" copper or brass rod as a buffer press the barrel out with a ratchet wrench.
Shop press
Place supports on either side of the front trunnion. Using a soft metal (Copper or brass) rod about 5/8" diameter or a steel rod with pennies or nickels as a buffer press the barrel out.
Removing the old receiver stubs and rivets
Now you will need to remove the receive stubs from the trunnions. Lock each trunnion in turn into the vise and using the angle grinder remove the rivet heads. Do this to both sides of the trunnions. With the heads removed you can peel off the receiver stubs with the vise grips.
Rear trunnion
Front trunnion
To remove the rivets from the front trunnion set it on it's side on the anvil of the bench vise and using a small punch knock the rivets out.
To remove the rivets from the rear trunnion you will need to drill them through. First you will want to center punch the rivets on one side to help the drill bit start. Lock the rear trunnion in the vise on your drill press, being sure that it is level, and drill all the way through the rivet with a .120" bit. Go very slowly, 1/4" at a time and use a lot of cutting oil.
To remove the rivets from the trunnion support it on the jaws of the bench vise and using 1/8" punch drive the rivets out.
To remove the rivets from the trigger guard you will start by locking it into the bench vise. Use the angle grinder to remove the rivet backs from the inside. Be sure not to damage the selector stop on the spacer plate. Once the rivets have been ground down use the vise grips to pull off the old receiver section.
Next lock the trigger guard into the drill vise and drill through with the .120" bit. Once they have been drilled they can be knocked out.
Removing the gas piston
If you are going to use a US made gas piston you will need to remove the original one. In most cases they are held in place by a rivet. You can locate the rivet on either side of the bolt carrier about 1/2" back from the front. It may be necessary to use sandpaper to see the rivet outline. Place the bolt carrier on it's side on the slightly open jaws of the bench vise and use a center punch to start the rivet out. Use the vise grips to finish the removal. Once the rivet is out you can unscrew the piston from the carrier.
The de mill is now complete and you should have this:
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