I had a ban era Armalite with 20" barrel (chromed bore). The barrel was fitted with a permenantly attached muzzle brake, and the rifle had the regular handguards.
I wanted to install a YHM free float handguard (the cheap one
). Anyway, I drilled out the muzzle device pin, and was pleasantly surprised to find that Armalite had threaded it under there.
I removed the muzzle device, gas block and old furniture. Removed the barrel, then reassembled using the YHM barrel nut etc. I used a new crush washer and an A2 style flash hider, and leveled the device carefully so that the flats were at 90 deg to the flat top receiver.
Rifle functioned fine, no gas leaks or other problems. I scoped it up and found that it shoots about 5" groups at 100 yds with IMI M855.
Previous to doing the work it shot 1.5" with the same ammo.
The only thing I can thinkof is that the rifle does not like the A2 flash hider - is this correct ? Anyone got other ideas ?
Weather has been too bad to go out again, so I thought I'd use the computer to get some info.