Assuming no ejector or extractor marks on the brass, then soft federal primers giving a false alarm is my bet.
Some pics to confirm would be great.
Type: Posts; User: Pommy
Assuming no ejector or extractor marks on the brass, then soft federal primers giving a false alarm is my bet.
Some pics to confirm would be great.
Have you measured the shoulders on fired vs unfired brass? That'll confirm or rule out headspace.
That said... any other pressure signs? Would expect to see other problems if excessive headspace...