Originally Posted by
Walks
My old NM Blackhawk in .45COLT was fitted with a .45ACP cylinder in 1984. My bore measures out a .4515 diameter. My .45Colt chamber mouths measure out at .451-.452, My .45ACP chamber mouths measure out at .451-.4515 .
I shoot a .454dia Lyman#454190 sized .454 in the .45Colt and a .452dia RCBS #452-201-KT sized .452dia in the .45ACP.
I have other loads I've tried, in both calibers. It does not seem to matter as long as the bullets are sized at least .452
The .45Colt load is more accurate then the. 45ACP load. By a 1/2 inch, I don't think it really matters.