26 December 2010
As you know, I usually use A2400 and SR4759 for my rifle loads and usually in a 1903 Springfield, of some conformation. From match benchrest shooting with them, I have developed the habit of holding the base of the cartridge down on the follower so that the bolt will slide over the ledge of the follower. This means my powder charge is generally laying spread out on the bottom of the case. I don't want those 4000 degree pieces of Al flying around the inside of the case.
I will admit that the hottest primers will give the smallest velocity spreads and SD of velocity, if the firing train has enough energy to fully detonate the primer. But I am not convinced that it has much to do with accuracy up to 200 yards. It doesn't make it worse but it doesn't make the groups better either.
Maybe if I was trying to ignite a compressed block of black powder, like the BPCR guys, or a compressed load of 50 BMG powder, it may make a difference. Again, the only time I have had better accuracy, at least in my loads, is the 45/70 in the trapdoor with minimum loads of shotgun powder. Then the Fed 215's and WW LR primers gave me better result, especially in winter.
I haven't seen a difference in accuracy with low SD loads of say 5-10 over ones that were in the 20 -30 range at 1500 fps either .When i shoot plainbase at 1200 or so seldom do i get top accuracy with wide velocity variations.I shoot pistol primers in all of my plain base loads lately.
I always liked the idea of the aluminum flying around to help ignite the charge.
I am going to try Dacron wad next time out.A Schuetzen i know guy swears it gives him best accuracy in big cases with little charges.The uniformity is about the same he says,but it protects the bullets base is the theory.Worth a try.