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1stmar · September 2, 2012, 07:27 AM

Going back over my logs from Fridays shooting I had made a note that 1 round in 10 had stiff bolt lift. the load was 36gr varget, 53 gr Sierra in 22-250. All rounds were chrono'd. I looked at the case today and I measured the shoulder. Sure enough the shoulder is .001 higher then the other rounds and there is an extractor mark. I'm pretty meticulous about my loading procedures. I measure each charge, case prep is the same, measure each bullet, measure the shoulders and mark any that are more then .003 pushed back. (usually neck size but at this point I needed to push shoulders back) if there is anything out of "spec" I will mark the case or bullet with a red marker so I know it prior to firing and can judge the impact of the failure. This cartridge was not marked as any type of failure (oval, headspace, runout , case weight, etc). So I'm pretty confident I didn't miss anything. Here's the other oddity: the velocity was not the highest (3651) and poi was in middle of the group. Sd was 20.7, es 40 and group size was .58. I have fired loads of 36.5 and 37gr with no signs of pressure.

My question is what could have caused the excessive pressure and why didn't it show up in the results (chrono, group size)?

September 2, 2012, 07:27 AM	#1
1stmar Senior Member Join Date: March 21, 2012 Location: Connecticut Posts: 2,378	Pressure signs... Going back over my logs from Fridays shooting I had made a note that 1 round in 10 had stiff bolt lift. the load was 36gr varget, 53 gr Sierra in 22-250. All rounds were chrono'd. I looked at the case today and I measured the shoulder. Sure enough the shoulder is .001 higher then the other rounds and there is an extractor mark. I'm pretty meticulous about my loading procedures. I measure each charge, case prep is the same, measure each bullet, measure the shoulders and mark any that are more then .003 pushed back. (usually neck size but at this point I needed to push shoulders back) if there is anything out of "spec" I will mark the case or bullet with a red marker so I know it prior to firing and can judge the impact of the failure. This cartridge was not marked as any type of failure (oval, headspace, runout , case weight, etc). So I'm pretty confident I didn't miss anything. Here's the other oddity: the velocity was not the highest (3651) and poi was in middle of the group. Sd was 20.7, es 40 and group size was .58. I have fired loads of 36.5 and 37gr with no signs of pressure. My question is what could have caused the excessive pressure and why didn't it show up in the results (chrono, group size)?