08-22-2012, 11:10 AM
Von Gruff,
In my testing, Wolf Small Rifle Magnum primers produced the most uniform velocities of all primers I tested. These include the CCI 400, 450 and BR4 as well as the Remington 6 1/2 and 7 1/2 and Federal 205 gold medal match. This was with IMR8208XBR and 81.5 grain Cauterucio bench rest bullets out of my Stolle Panda. I've seen ten shot strings with standard deviations of 6 fps and groups in the ones.
BW,
I believe what you are seeing with the Remington 6 1/2 primers is due to the larger firing pin hole of an AR bolt leaving a gap that the pressure can force the primer cup material into. I see this as well with my ARs but not my bolt rifles that have a very precisely fit firing pin hole in the bolt face. For these bolt rifles, as peak pressures are approached, the primer is very flat, no radius left but no cratering either.
Bob
In my testing, Wolf Small Rifle Magnum primers produced the most uniform velocities of all primers I tested. These include the CCI 400, 450 and BR4 as well as the Remington 6 1/2 and 7 1/2 and Federal 205 gold medal match. This was with IMR8208XBR and 81.5 grain Cauterucio bench rest bullets out of my Stolle Panda. I've seen ten shot strings with standard deviations of 6 fps and groups in the ones.
BW,
I believe what you are seeing with the Remington 6 1/2 primers is due to the larger firing pin hole of an AR bolt leaving a gap that the pressure can force the primer cup material into. I see this as well with my ARs but not my bolt rifles that have a very precisely fit firing pin hole in the bolt face. For these bolt rifles, as peak pressures are approached, the primer is very flat, no radius left but no cratering either.
Bob