I've have read threads recently concerning chamber throat dimensions on N frame 45 Colt revolvers and how to estimate which ones might be appropriate for cast bullets. A while back, I did the same for 44's. My present question is, "Do the same general rules apply for revolvers chambered in 45 cap, or did they manage to avoid the generous throat plaque of their 44 and 45 Colt brethren?"
I have a model 25-2 in ACP and a .451 FMJ will free fall through the throats with no resistance. I shoot .452 cast bullets in auto rim brass and it still is more accurate than my eyes. I would not have thought it would shoot as good as it does. I have a model 22-4 (ACP) that has throats that the same .451 FMJ has to be helped to pass through them. It also shoots good with the same .452 cast bullets.
I have a 25-2 with very generous throats...like .456''. If I was shooting cast bullets in it they would have to be at least .454" and from past experience that can present problems with chambering. I am currently loading Berry's .452" plated bullets and it shoots them reasonably well with no chambering issues.