Home Forums Hunting & Shooting AR and Tactical Rifles Tac 20 build (pic heavy)

On to installing the barrel extension permanently. I made this barrel vise years ago, and it's pretty out of the way attached to a workbench in a back room so I've never bothered to move it. The two 5/8" fine thread grade 8 bolts give LOTS of clamping pressure, and with a properly fit set of steel blocks it'll handle 175+ ft-lb easily without slipping or marring the barrel. I make those steel blocks for each barrel size by boring a hole through a solid block then sawing it in half. With a smooth finish in the blocks, it doesn't even scratch the polished surface of this barrel.

I use red 271 Loctite on the barrel extension threads, and torque to 100 ft-lb. Torque is applied via 1/2" drive torque wrench and that Brownells barrel extension tool pictured at the beginning of this thread (in the receiver lapping post).


Installing the extension pin is straightforward. I just cut a piece of 1/8" O-1 drill rod (annealed, not hardened) to .185" with a chamfer on both ends, and tap it in place. The barrel extension hole is sized to be the right press fit for 1/8" rod.

Comment on this part - some companies install hardened pins here. I don't like that because I've had to fix a couple that cracked and broke (from abuse, but still). An annealed pin is much easier to remove if it's damaged, and O-1 is plenty strong even in its softest state. This pin is only there to locate the barrel in the upper so the feed ramps are lined up, it should never be stressed by barrel or muzzle device installation (one reason I really do not like receiver blocks, use an extension tool / reaction rod instead).


This barrel is now ready for drilling the gas port hole, that'll come in the next update. The top barrel is my extra 243 LBC blank, still unprofiled at 1" diameter.