Quote Originally Posted by Delhiguy91 View Post
I actually tried both of those primers (among others). I have since switched to Lapua brass and I'm using cci450 primers with similar results.
more thoughts; This thread has me baffled also when factory ammo outshoots a variety of handloads and testing. We all know that every barrel has a mind of its own. case point; my better barrel loves 41.8 gr h4350 in Starline (heavier brass with no pressure signs). The same load in the shorter barrels shows bad pressure signs (hard lift & ejector marks) and didn't shoot well besides.
Using FC brass (12-13 grains lighter than Starline) the two short barreled rifles showed no pressure with more powder (42.5) and shot faster as well as better group wise than anything tested in the Starline. Maybe the Lapua brass is not an answer in your case.
What velocity did chrono show with the factory loads compared with your testing? Trying to pin point any one single cause is frustrating at least, finally finding the solution is where its all at. The guys on this forum all work pretty hard with problem solving, you've come to the right place.