[caz223]

A firm taper crimp isn't necessary, in fact it's prolly part of your problem.
If your bullet has a crimp groove then maybe if you use a roll crimp die in the correct size, then a firm crimp would help.
Overcrimping is easy to do, esp with soft bullets.
A couple more questions....
With no moonclips, do your rounds seat flush, or fall below flush?
If they fall through and stop at the end of the chamber, then you got a 625 chambered in .45 colt.
If the bullets seat and look just like they would if you have the moonclip, then it's ok, and it's the right caliber.