I've had two Blackhawk convertibles, both 4 5/8". Both shot .45 Colts a lot better than .45 ACPs, but I never loaded the ACPs especially for the Blackhawks, the ACP ammo was loaded for my 1911s, and just used in the RBHs for fun and to see how they shot.
I liked both of them, but since I mostly shoot ACPs anyway, I just traded them off for this or that. I suspect the cylinder jump was the culprit for the poorer accuracy I got with the ACPs, but it might have been my taper crimped loads just didn't fit the cylinder very well. Both shot the the .45 Colts quite well. I just decided to go another direction.
