What bullet size is best, some books recommend .452 others .451.
Does .oo1 really make a difference.

well that depends on the size of your barrel. i believe barrels are supposed to be .452 so a jacketed bullet with a diameter of .452 would be the best, now if you are shooting cast bullets then .453-.454 would be best as a general rule for cast bullets is .001-.002 over barrel diameter is best. slugging your barrel would tell you what diameter is best (slugging is the process of taking a slighlty oversized chunk of lead and pushing it down the barrel so that when it comes out the other side you can measure it and determine barrel diameter). Of course just as easy would be to shoot some .451 bullets and some .452 bullets and determine which ones shoot better in your gun. and come to think of it ive never heard of bullets sold at .451, then again i dont load the 45ACP.

It CAN!! Slug your bore, and use bullets just as large (jacketed), or up to .002" over, if using cast, PROVIDED ROUNDS SO LOADED WILL CHAMBER EASILY!

The .45 ACP is notorious for wearing out barrels prematurely, IF USED WITH UNDERSIZED BULLETS that permit gas blow-by, and gas cutting of the barrel steel!

Black Magic,

There is a little confusion about the diameter of .45 bullets. Most of it comes from the .45 Colt. Pre WWII, the colt had a .454" bore. Post WWII, the bore was standardized at .451", same as the .45 ACP. Jacketed bullets should be .451". Cast bullets are sized .001" larger than jacketed bullets, for .452". I hope that this is of some help. Good luck and God Bless.