Luth-AR A1 Compensator Lock Washer

This is the lock washer Luth-AR lists for A1 style compensators. It goes on the barrel threads behind the device and takes up the tension when the compensator is torqued into position, so the device stays indexed instead of backing off under recoil.

It is a small hardware item that gets lost, bent or left behind more often than it gets worn out, which is why it is worth having a spare in the parts bin before you start a muzzle swap. Nothing about the job is complicated, but a missing washer stops it cold.