Junk used parts

[Joseph Scott 0]

I have received two barrel rear locking collars to assemble for a customer. Both are used, from a major parts dealer. One has been shortened by .070" on the shoulder face. This is not useable due to insufficient room for the bolt head to rotate and lock. It looks OK but has been machined by someone trying to correct headspace. The available parts now remaining are the culls and new purchases by dealers. They don't know or care about dimensions. Save your receipts to try returning such items. I have been seeing more and more junk parts in the last two years, also guns that will not function due to old, bad gunsmithing..

To correct headspace, you must machine the barrel shoulder/threads back one exact turn, face off end, cut bevel, cut entrance radius, machine extractor cut and then install a .062" spacer behind the center collar to put barrel back in correct operating position, finally ream chamber for headspace. If you do not install the spacer, the rear collar will be sitting too far forward for correct lockup. Miss the cut-back by a few thousands and the front sight will not be upright.