The 308 has a moderate load of 41.7IMR4064/168SMK, extracted fine last week at 90 degrees. Nothing different (ie no cleaning , same box of loads, etc) and now at a cooler 75 degrees I have to knock the bolt to get the fired brass out. Using the headspace comparator, the brass is stretching from 1.624" when sized to 1.628-1.630" after firing (headspace is set at 1.628"). What is strange is that brass fired last week and 1-2 months ago without sticking problems (have not touched, and it is also 1.628"-1.630") now exhibits the same difficulty. I would swear the headspace has shrunk, but I cannnot measure any evidence of that. Cleaned the chamber with a brush and that does not help. For the first time I see "pock marks" on the bolt face, maybe a burn mark; I will pull the bolt head and polish these blemishes since I cannot find anything else different. Any other ideas?
Finally got this back to the range and after cleaning the throat well (maybe carbon ring) and tightening the headspace back .004" to .003" clearance the same loads shot without and signs of pressure again. Looks like the longer headspace was the culprit afterall.
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