Ive got one in a 5.45X39 carbine..... its ok, other than the special bolt (pads on the back for anti tilt) and bumper where the gas key would be on a std bolt. I bought it because I fire the Russian surplus 7n6 rounds in it, which are still corrosive. I would not bother with one for non-corrosive ammo.....



As an addendum, mine is an adams upper, and the hand guards do have to be hogged out on them to work......