The .45 ACP and the .45 Auto are the exact same round.
I saw a similar thread on 380 auto/380acp and one reply stated they were the same and another reply stated to use only what was exactly stamped on the gun barrel.
If the same holds true for .45 Auto vs .45 ACP, I'm still unsure since I've seen some guns stamped .45 ACP and the Ruger (SR45) that I'm waiting to get is stamped .45 Auto.
I haven't been shopping yet for .45 ammo, so I suppose the question would be answered if I see boxes labeled .45 AUTO and labeled .45 ACP, in which case I would get the .45 AUTO for the Ruger.
Wish there wasn't so many "variations" between same caliber bullets.
Ace
The .45 ACP and the .45 Auto are the exact same round.
Yes
There are a few other 45s so auto or acp is the only thing you want to see after 45 unless you want to use +P,which will be after auto or acp.
9mm has about 7or 8 different varieties but you'll normally only see 380,9mmLuger (or Parabellum which is also 9x19) and sometimes 9x18 in the majority of stores.I believe the 9mm Corto and 9mm Largo are the original name for the 380 and 9x18 but don't recall which is which.There;s also the hotrod 9mm Luger offshoots the 9x21,9x23 and 9x25.The 45 seems easier now doesn't it?