I've read several defensive gun books lately that have briefly mentioned revolvers chambered in .45 ACP. Could someone please enlighten me as to just exactly how in the hell a rimless cartridge works in a revolver?

i dont know for sure but i think you have to use moon clips. i dont like the idea for a defense gun.
http://froogle.google.com/froogle?q=moon+clips+45+acp+revolver&hl=en&lr=&sa=X&oi=froogle&ct=title

Moon clips hold the rounds so they can be loaded and held in place. Then it acts as a normal revolver. It is also a very fast way to load and unload a revolver. There are 9mm and 45ACP revolvers.

You can also use "45 auto rimmed" brass.

My S&W .45 ACP revolver headspaces on the case mouth, just like the chamber in a semi-auto. You can shoot it without moon clips but then you have to pick the empties out with your fingernails or push them out with a pencil. I also shoot auto rim that I reload for it. With either half moon or full moon clips it reloads very fast. No speedloader to mess with since the whole thing stays in the gun when you load and comes out when you reload.

My gun is a 1955 Target which later turned into the Mod. 25 S&W when they began assigning model numbers. I bought it used in 1960 and it was actually made in 1955. Sweet shooter.

Ahh, so that's what moon clips are for. I've heard the term thrown around, but didn't bother to find out what they were.

Thanks for the good info guys.

Very fast indeed if your skill is up to it. There's a well known video shown first on the history channel and now floating around cyberspace of champion shooter Jerry Miculek putting 6 .45 acp rounds on target, reloading, and putting 6 more on target from his S&W model 625 in under 3 seconds. Moon clips provided enough of a speed advantage to prompt IDPA to separate revolvers into 2 classes, SSR for speed loaders and ESR for moon clips.

I saw Jerry in commercial for S & W this morning. I also saw him on TV when he boroke the record shooting reloading and shooting again(I think that was American Shooter).

One can get the cylinder cut to accept moon clips even for rimmed ammo, to get the speed avantage of the full-moon clip. There's no speedloader button to push or twist, you just throw the whole unit in there & close the cylinder. I've seen video of Jerry Miculek reloading a 625 'way faster than I can do a mag change with a 1911, I'm not terribly slow at that.

Is to get a 454 revolver with a spare 45 ACP cylinder. You can then handload up 45 Super loads (using 45 Super brass, of course!!) that will smoke more than Fidel Castro. I have NO idea how hot you could go in 45 Super with a 454 revolver, but I have a plain old $350 NIB EAA 45 that eats 45 Super ammo and puts a Hornady 185 grain XTP out the front at 1250 FPS with a 4.4" barrel. The unofficial factory spec for 45 Super ammo on the Ace Custom 45 website is 230 grains @ 1200 FPS.