Weight and consistency of alloys?
The bullets above are made of two different alloys, soft lead in the nose and WW's with some tin; sometimes they don't even "look" good. I have no idea what they weigh from one bullet to the next; out to 100 yards it should be negligible on paper, provided they are reasonably close.
Are you fluxing while casting?
I think diameter in relation to the throat (and whether your dies are swaging the bullets) and distance to the lands will pay greater dividends. Of course making the best bullets you can never hurts anything.
These loads slightly engage the rifling with a slight "hitch" to the lever, sized .457, nose first. They might shoot a little better in the 1895 if they were a little fatter, but the 458 SOCOM throat won't eat anything larger fouled up a bit and soft seated, so expediency wins.
