How many thousands of an inch larger than bore diameter can hardcast bullets be ? I generally aim for about .002 over, but my last batch is almost .005 over. Im casting for a new rife, BLR in 450 marlin. Havent slugged the bore yet but expect it to be .458. In my 45/70s I always shot .460 , but this latest batch is .463 on average. Are these to big?? They are powder coated. Mold is a Lyman 457163
For starters - size your bullets to what you want them to be, rather than just depending on mold diameter; it's best to have them all start at the same diameter rather than varying a bit in as-cast size. Sizing irons out irregularities in the powder coating as well.
As for how big they can be - that depends on your chamber. In some, .005" over is fine. In a lot of guns though, that will be too big for a loaded cartridge to fit in the chamber. Forcing it in anyway will drive up pressures and can be the difference between a safe load and dangerous pressure. A simplified way to determine that is check your fired cases from that gun; if your cast bullets won't fit in the fired cases easily by hand, they are too big.