3A. Fitting Barrel Extension to Upper Receiver
This is a little out of order with the other HOW-TO's but here it is anyway.
Most people use Locktite for this step and it is a lot easier, but...This is the ULTIMATE AR !!! So, we're gonna do it right.
First we get to measure the Inside Diameter (ID) of the upper where the Barrel Extension slides into, then we will measure the Outside Diameter (OD) of the Barrel Extension. Check the Barrel Extension for any burrs or high spots. If the difference is .0025" or less, you are good to go, no need for a shim.
Now we get to do some math.....
Then we make a trip to the local Industrial supply house and get some Stainless Steel shim stock of the correct thickness (in this case .002"). Get a pair of sharp scissors and cut the shim to fit around the barrel extension (make sure it clears the feed ramps).
I take a flat stone and knock the burrs off the shim to make it flat again.
Wrap it tightly around the extension, with the seam to the right or left side of the rifle (NOT the top or bottom), secure it with a piece of tape to get it started (remove the tape before you slide it all the way in). I put a drop of blue Locktite in the seam right before I put it all together
You can heat the receiver up a little if it's a little tight getting together.
DON'T FORGET to install the ejection port cover before the barrel nut!
Install the barrel nut and torque to spec.
This is a little out of order with the other HOW-TO's but here it is anyway.
Most people use Locktite for this step and it is a lot easier, but...This is the ULTIMATE AR !!! So, we're gonna do it right.
First we get to measure the Inside Diameter (ID) of the upper where the Barrel Extension slides into, then we will measure the Outside Diameter (OD) of the Barrel Extension. Check the Barrel Extension for any burrs or high spots. If the difference is .0025" or less, you are good to go, no need for a shim.
Now we get to do some math.....
Then we make a trip to the local Industrial supply house and get some Stainless Steel shim stock of the correct thickness (in this case .002"). Get a pair of sharp scissors and cut the shim to fit around the barrel extension (make sure it clears the feed ramps).
I take a flat stone and knock the burrs off the shim to make it flat again.
Wrap it tightly around the extension, with the seam to the right or left side of the rifle (NOT the top or bottom), secure it with a piece of tape to get it started (remove the tape before you slide it all the way in). I put a drop of blue Locktite in the seam right before I put it all together
You can heat the receiver up a little if it's a little tight getting together.
DON'T FORGET to install the ejection port cover before the barrel nut!
Install the barrel nut and torque to spec.
