I did the full length sizing of .284 Win brass to make it 7.5 Swiss. After crushing case #1, the next 21 came out fine. The problem came when I tested the seating depth in the rifle with a dummy and a dry erase marker. I read in one of my manuals that when properly seated the dry erase residue should not be touched. I set the COL at 3.050 and then tested it in the chamber. When I removed it, the bullet had clearly contacted something and was 2.933 in overall length. Moving it in to 2.893 resulted in no bullet-rifling contact (bullet is a 168 grain Sierra BTHP) but this seems much shorter than the recommended COL of 3.060 for this load and thus I'm worried about overpressure. Anyone give me some advice on how to proceed?
It looks like the bullet is fatter than the GP11 so perhaps that is the problem?
It looks like the bullet is fatter than the GP11 so perhaps that is the problem?
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