Home Forums Hunting & Shooting Express Rifles and Big Bores Only The great 458 Winchester. Everyone should own one at least once

Sir Jerry,
Great idea.
AA-2015BR is sometimes listed with the "Bench Rest" designation for its consistency and ignition characteristics.
It is a single-base, extruded powder, burns faster but requires less powder weight
to get higher velocity AND pressure than the AA-2230 or AA-2460s, both double-base spherical/ball powders.
Interestingly AA-2460s has that "s" listed sometimes too, which I SWAG is to emphasize that it is the un-flattened, fully spherical form of AA-2230.
AA-2230 is the one with about half of its granules "pre-compressed."

76 grains of 2015 probably gets slightly compressed like the max loads for 2230 and 2460 with 400-gr bullet and 3.140" COL
as shown in the table below.
2015 gives the highest MV and the highest (submaximal) pressure in the modest data below for 400-gr Barnes "Old Original" SSSP:







AA-2015BR should be a good one.
Only drawback might be temperature sensitivity. I don't know about that being any problem for most situations.

Burn Rate charts below suggest other good neighbor powders: Anything good in the .223 Rem and 5.56 NATO.
Alliant Power Pro 1200-R would probably be a humdinger with the 404gr Shock Hammer.





Sheesh, I wish I could do them all !
Just goes to show what a great cartridge the .458 WM is with so many good powders.