I have some 410 gr .410 conicals for my .410 white. I was going to shoot them in a 1:20 twist in a sabot but the sabot didn't look like it was long enough. At least the bullet didn't want to stay in there very well. I could send you some 538 gr but they are sized to .448 so they would probably be a little loose in a .45 unless you fouled the barrel good with a couple squib loads. I doubt you could get them to stay in a sabot to shoot them from a 50 cal due to the length