ORIGINAL: newguy23
ORIGINAL: peeker
The .45 ACP is NOT a straight walled pistol cartridge. Wouldn't want you to get yourself in alot of trouble and loose a firearm because of a mis-understanding on your part.
The 45 ACP (Automatic Colt Pistol) IS a straight-walled pistol cartridge. Matter-of-fact it is a "rim-less" cartridge, the only one I can think of off the top of my head.
A straight-walled pistol cartridge refers to the fact that there is no necking (down) to a smaller caliber bullet, such as most rifle cartridges. The intent of the rule is to rule out the use of single-shot pistols which can shoot rifle cartridges, such as the TC Contender chambered in a .308.
So by definition (ethics regardless) anything with a straight-walled cartridge, larger in diameter than or equal in diameter to .357 inches is perfectly legal. This makes something like a
9mm, .40 S&W, and a .45 ACP legal.
I'd have to agree with newguy23's interpretation of the rule and say that all of the above cartridges are "legal" but that doesn't make them ethical in my opinion