bwinters -
I had one box of 120 grain partitions when I bought the gun. I did a fast test with those last spring.
All brass is WW +P from the same bag o' 50, all groups were at 100 yards. The first 15 were 3 shot groups, the last with H4350 was a single 5 shot group which used up the box of bullets.
Fed 215M primers, H414
39.5 grains, 4.8 inches
40 grains, 1.67 inches
41 grains, 1.79 inches
42 grains, 1.26 inches
43 grains, 1.05 inches
Fed 210, IMR 7828
44 grains, 1.09 inches
45 grains, 0.93 inches
46 grains, 1.17 inches
47 grains, 1.12 inches
47.5 grains, 2.5 inches
Fed 210, IMR 4831
40 grains, 1.25 inches
41 grains, 1.76 inches
42 grains, 1.16 inches
43 grains, 2.19 inches
44 grains, 1.92 inches
Fed 210, H4350
42 grains, 1.84 inches
I've had two other .257s that also did their best work with 120s (Partitions and the now-discontinued Hornady FB HP) with 43 grains of H414 and a federal magnum primer. Based on that, plus this brief test, I hope to find another box of 120s and do some shooting on past 100 yards.
I haven't seen any more 120s. The 100s and 115s have shot poorly, 2+ MOA, in this gun.
My plan for it right now is to shoot the hell out of it as a varmint rifle. I've got a bunch of lighter bullets and a few Accubonds left. If I run out of bullets before I find 120 grain partitions I'll sell it, if the 120 grain partitions show up sooner I'll try them s' more and decide keep or sell based on what they do downrange.
