I recently tested two different primers to see which would give me the best accuracy, lowest extreme spread, and standard of deviation. I tested CCI BR4's agains CCI 450 mag primers in a 223. All components were identical except the primers. Same Brass from the same lot, Same bullets from the same lot and the same powder. I shot 3 five shot groups with each primer and compared the chronograph difference and accuracy difference. At least in this one rifle it is not worth higher cost of the BR4's. The CCI 450's beat them by a narrow margin in all aspects. The S.D. was less by 5. The extreme spread was less. and accuracy was just slightly better with the CCI 450's. I know this is a very small test sample and your results may be different. Anyone else done this with measurable results? DW

This could vary with powder, cartridge, and gun. I think all that it proves is that sometimes one primer works better than another. Obviously, it is not always the "benchrest" primer, nor is it always the "magnum" primer.

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Originally posted by Stonecreek:
This could vary with powder, cartridge, and gun. I think all that it proves is that sometimes one primer works better than another. Obviously, it is not always the "benchrest" primer, nor is it always the "magnum" primer.

This is very true. Even in the same rifle, diff. powder/primer combos mya be more accurate. My 338-06 thirves on 4350 & CCIBR primers. With RL15, it prefers Fed. std. primers, but primers can make a measurable diff. so I try several when I get a good load worked up.