Home Forums Reloading Big Game Rifles Small vs Large primers for Creedmoor

A shooting partner and I did a SMALL test of this in 6.5 Creedmoor with the Pressure Trace and a chrono somewhat more than a year ago. There was not a noticeable (I don’t recall whether I did any statistical analysis, but if I did I didn’t save it) difference in pressure or speed between Lapua and Norma (SR and LR primers, respectively) cases with the same charge of 4451 under 140s, using Wolf SR magnum and Wolf LR primers. We did the test in quite moderate weather, neither hot nor cold.

THIS WAS NOT AN ALL-ENCOMPASSING TEST, NOR WAS IT EVEN A MODERATE-SIZE TEST. DON’T COUNT ON THIS RESULT WITH EVERY COMBO YOU MIGHT TRY. The Lapua and Norma cases we used were both non-ballon-head cases, meaning the bottoms of the cases are flat on the inside. Hornady cases, at least the ones I’ve always received, _are_ ballon-head, so there would be a capacity difference between them and the Lapuas that one would expect to make a difference in pressure.