I use plain old electrical tape, I just make sure the muzzle is completely covered, then I tape over the ends of the tape in the opposite direction so it can't come loose from the barrel, I haven't had any problems yet, been doin' it that way for years. The gas blows the tape off the muzzle before the bullet exits the barrel so nothing to worry about there, and I've noticed no change in POA shooting from a taped muzzle whatsoever.
