I know this subject has kinda been beat to death but I'm looking for information from other GI owners who has had the problem of disappearing head space in their guns. I got a new GI that started out at .12 headspace and then went under 10 in a hundred rounds or so. I got +2 rollers and it went back up to 12 and then after a hundred or so rounds the .10 won't fit. I bought a HK complete bolt assembly and when put in gun will not accept .10 gauge. I'm calling PTR on Monday to speak with them concerning the issue. Checked several times and there is no crack on the trunion. Any suggestions on how the conversation should go from people with a similar problem that was corrected will be a big help. S.N. G101**. I like the gun well enough that I am going to do what ever it takes to get it right. Shoots great but I am concerned with the above mentioned problem.