All of the allowable specs and tolerances from even ONE manufacturer (except for perhaps Savage and White) would be scary. Bore diameters must be determined for each individual rifle even from the same model and manufacturer (and then it may vary as you go down the bore).

I've got one Encore .45 that will engrave a copper coated PowerBelt on loading and another that would let the same bullet drop like a rock (were it not for the plastic base).