SSL
Gold $$ Contributor
Another round you may be interested in is the 45 Schofield. Curious about your barrel diameter. 45acp is .451 and 45 colt is .456. The Schofield is .452. All the differences in 45 drive me mad. 45/70 is .458 and I reload all 3.
I believe modern manufacturers have standardized on .452" for .45 Colt as well. You are indeed right that original Colt bores ranged widely in specs, from .452 to .456" and chamber throat dimensions not always matching the bore diameters. My Ruger Blackhawk bore measures .452" (as do the cylinder throats) and I use .452" un-sized (.453" out of the mold) Lee 255-grain RF cast bullets (260 grains from my metal) and get minimal leading from 800 to 1,100 fps.