i was out shooting recently with a friend. both of our loads are carbon copies of each other. both loads were ladder tested and it just so happened that we needed the same powder charge. the only difference being brass. my loads call for 44.8 grains of rl15 with a 178 amax, cci br2 and a hornady match case trimmed to 2.000''. his loads are exactly the same but with lapua brass thats relatively fresh compared to my old brass. the loads come from the same dies, press, cans of powder and boxes of bullets. to boot, they are usually loaded on the same day, shot on the same day on the same targets. it seems to be a general consensus that lapua blows hornady out of the water but in both of our rifles the hornady brass has a slight edge at 3/8 moa vs slighly sub 1/2.

my best explanation is that my brass has been worked in. i was fist thinking it had something to do with case capacity but his rifle was specifically ladder tested with lapua and 44.8 was found to be the very best so in theory the better brass with a optimised loads should be more accurate.