.431" .44mag bullets GTA?

[Sgt.RockRules04]

Hello CGN's, I'm a .44mag nut (Marlin 1894 lever & Ruger Super Blawklack pistola) & I've tried Campro & DRG bullets, all shoot ok but, not great. I haven't slugged my barrel but know several friends who have varied sized .44mag barrels. I'm looking for .431/.432" projectiles in the GTA & Niagara regions? Anyone know where to find these? Also, I'm using these components; CCI large pistol primers & Alliant 2400 powder.(DRG-.430 & Campro-.429")
Thanks if someone has info. SgtRock, out.