I shoot a custom 257 on a springfield 1903-A3 action and i'm using winchester brass, winchester primers, 41.5 grains of IMR 4350 powder, with sierra gameking 120 grain hollow points. It isn't the most accurate load in the world.

Does anybody have any loads for the 257 Ackley Improved?

Thats the starting load, according to the Nosler #4 manual, for the 120 gr nosler partition. Shows vel at a little above 2600 fps. I'd buy the manual and have a good reference tool rather than asking for someone elses brew. Your wildcat should be treated as a one of a kind simply because there can be variations in the chamber spec's per the smith that made it...Enjoy, it's a terriffic cartridge : BT53

With ligher bullets, my rifle (and several others) is great with H4895 and a standard primer.