The Sight 1911 .45 ACP Page
Having established the almost universal agreement that the .45 ACP is an acceptable personal defense cartridge (kind of like proving the ocean is wet), are there negatives? Sure there are. For one thing, the .45 ACP is big and heavy. The same characteristic that makes it so admired by the big hole school also makes it heavy to carry and bulky, resulting in fewer rounds being available in compact handguns. A fully loaded Thompson submachine gun is fairly heavy if you have to lug it around through a hot jungle all day. Some people find the recoil of the .45 ACP punishing although I'm not one of them (I actually prefer the recoil of the .45 ACP over the recoil of the 9mm). The penetration of the .45 ACP 230-grain FMJ bullet is 26" in ballistic gelatin, making it problematic and dangerous as a personal defense load. The threat of over-penetration with the military round necessitates the use of hollow points for LEO and civilian PDW applications. Some of the older 1911 pistols don't like hollow point bullets very well and have to be throated and have their feed ramps polished for reliability. And last, there is the cost. The .45 ACP is expensive as pistol cartridges go, often $3-$4 per box more than 9mm or .38 Special
Not wanting to start an argument, but .45 acp 230 gr. does some serious penetration. 26" of ballistic gel is probably more than enough to give an exit wound.
If my memory is correct (and it frequently isn't), .223 only has about 1/2 that much penetration.