Get a good reloading manual that explains the process and gives the dimensions for loading for a .45. The previous advise about belling the mouth and then crimping is correct. Now for lead bullets the bell is important as otherwise the brass will shave the bullet base when you try to seat it. With jacketed bullets, I often do not set the die to bell the case at all and I can seat them just fine while working the brass less so it will last longer.

The other thing that is important is overall loaded case length. There is a max length for the .45 and it does not sound like you are actually measuring yours with a caliper. Make sure you do this, you are affecting the chamber pressure if you are seating the bullets too deep.