120 grain partition, 43 grains of H414, Fed 215 primer in WW brass.
Surprisingly to me, only 1 of the 4 .257s I've owned has shot 100 grain bullets well. Most did well with 75s and 120s, less so with 87s and 115s, and sucked with the 100s.
The one rifle that did well with 100s was the most recent. I shot 48 grains of H4831 under a 100 grain nosler, b-tip and partition both did very well with the same charge, same cases, same Fed 210M primers.
Tom
