Watch out on what FH you use or get on a rifle. About four years ago I purchased a couple FH off of GunBroker. The seller said they were GI and I had bought some items from him in the past, so I though they would be OK; (note he is still selling M14 parts on GB)? I noted there was a strange color change in one area, however when they arrives they passed the ring test so I though they were OK. About 2 1/2 years later I finally got around to finishing the build on my LRB M1A/M14 super match and I used one of those FH in the build. It worked OK for the first 50+ rounds then bang, strange noise and the round blew it in half. I don't know if they are Chinese, cheap copies or something else. I called LRB and talked to Lou and purchased one of their GI/NM flash hiders, everything good, now However watch out for the parts on the market. Caveat Emptor!