Hi Jeff - I'd use a 500gr. with gas check. The hardest actually needed for 2,000fps through 2,200fps in a WM is normal WW metal. You can drop them through a slit towel into a bucket of water straight from the mould if you want as that will harden them some. Size and luvbe right away as over 12 hours, they'll come to full hardness. Sizing and lubing after they've hardened, will anneal them. That's the way it is.

Use only real WW alloys, not zinc, not pure lead. Zinc weigths will have a Z on them while the pure ones are the weights that stick-onto mag wheels. The real WW with clips are the ones you want.

I've used straight WW to 2,200fps in a .458 without any leading and 1" accurate at 100 meters.

I'd use H4895 only as it will handle ful charges, less than full charges and all the way down to 50% of a full charge.

IMR4895 is not H4895. Use either magnum or standard primers, didn't matter in any of my guns.

Since using a .459" sizer, not .457" or .458". The .459" will shoot very well - has in every .458 or .45/70 I've tried and now my .45/60 as well - all running 1" or under with WW bullets and H4895 powder. I've also tried Reloaer #7, but being a faster powder, the charges/speeds cannot be as high as the pressure generated outruns (is to much for) the WW alloy.

For a cheap mould that shoots well, the Lee 500gr. with gas check has shot in every .458 and .45/70 I've tried it in - at least a couple of each. I've had that mould since 1979 & it still works. Beeswax on the rubbing parts - just barely a touch with a sliver of wax is all it takes.