[Unclenick]

I expect this is a tolerance problem. If the bullets are even slightly generous, say, .4512" diameter rather than the nominal .4510", it follows that barrels made with no real freebore will often be narrow enough so that this will cause the bullets to jam the throat. If you want, have a gunsmith just touch the throat with a .45 ACP throating reamer. That will give you a short, round freebore and tend to make for less fouling with lead bullets anyway.