.45 ACP v. 45 LC (DO NOT START A FIGHT)

as the OP seems to understand, the longer case allows lower pressures, with matching velocities... I have a Blackhawk I converted to 45 Colt, & had a 45 ACP cylinder made for it, that shoots 45 Autorim & I find I can load them hotter than 45 ACP would be in a 1911, but if you are reloading, you might as well shoot 45 Colt... ( say's the guy with a custom autorim cylinder... sometimes variety is the spice of life )

butt... I'd never say that to my wife :o
 
Looking at the specs for commercial Ultramax "Cowboy" loads in .45 Colt, they offer a 250-grain bullet at 750 fps, and a 200-grain bullet at 765 fps. Respective muzzle energies are 290 ft-lbs and 300 ft-lbs. Winchester's Cowboy load is a 250-grain bullet at 750 fps, generating 312 ft-lbs of muzzle energy. (Don't ask me how two bullets of the same weight and traveling at the same velocity produce different muzzle energies. I'm just citing the specs I found on-line.)

Standard Winchester USA .45 Auto (ACP) is a 230-grain bullet at 835 fps, generating 356 ft-lbs of muzzle energy. Slightly hotter than the "Cowboy" loads, but not earth-shattering.

For comparison, Winchester's "regular" Super-X .45 Colt load is a 255-grain bullet running at 860 fps, generating 420 ft-lbs. And that's not a plus-P loading.

I don't think plain-vanilla, commercial .45 Auto is likely to do any harm to a modern SAA clone, or to a Pietta 1858 Remington clone. I own one of the latter, with a .45 Colt conversion cylinder from Kenny Howell. I didn't know anyone offered a .45 ACP conversion for the Remington clones (probably didn't back when I bought mine).
 
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OK. There's some peculiar stuff going on when you shoot a short autoloader cartridge from a long revolver cylinder.

FIRST, I don't think the 45ACP is a good idea in the converted front-stuffers...not unless I knew a lot more about the metallurgy being used in the 1858 clones by Pietta and Uberti. I would be curious enough to get a Rockwell test done on the frame as that would tell a lot.

Let me confine my comments to post-WW2 Colt SAAs, Ruger's New Vaquero, DA S&Ws and other guns known to be tough enough for full-power jacketed 45ACP.

The 45ACP has some interesting advantages over the old 45LC, to wit:

* For factory defensive loads, the 45ACP is still getting the very latest bullet tech from Federal, Winchester and others. Federal's devastating HST "police sales only" critter ships in 45ACP as does the barrier-penetration beast Hornady calls the "Critical Duty". There are others worth mentioning. These loads don't ship in 45LC.

* Reloading is faster and extraction is faster - DA or SA. On a DA you can use moons. On an SA you can thumb rounds into the loading gate out of 1911 mags or the like - not exactly "the cowboy way" but it works. And the tapered rounds extract faster and more reliably.

* Weirdest of all, the ACP gets a speed boost of sorts when traveling through the long smoothbore section of the cylinder that is "tight to the bullet". I don't know how much in a 45. I did some research on the 9mmPara (assuming a real 9mm-spec barrel as opposed to .357) and found that a 2" "snubbie" S&W was producing velocities on par with a 4" barrel Glock. That's impressive because a Glock has no barrel-to-cylinder-gap AND uses a nice poly-rifled hammer-forged barrel that tends to "spit fast". I would not have believed they were a wash but tests show otherwise. I believe this is due to the "tight smoothbore" going on for about 3/4" of travel, with zero (or close to it) gas losses via blowby. Now again, I don't know how much the boost is on a 45ACP in a full-sized gun, but I'd be willing to bet that a Ruger NewVaq in factory 45ACP with a 4.68" barrel is going to spit out rounds faster than a 5" 1911. Maybe a lot faster. Will it make up for the reduced case capacity vs. the 45LC? I doubt it, but...it's not impossible in similar weight loads. In the heavyweights suitable for four-leggers the 45LC will likely still pull ahead but...not for social use I don't think. Not given the slug development that's gone into 45ACP police use rounds...

It was this research that told me that I'd be happy converting Maurice the FrankenRuger NewVaq to a true 9mm complete with Douglass .355" barrel from a 357. True, power was going to drop but in terms of "social use" the per-round effectiveness could be bolstered by the police-grade 9mm+P/+P+ rounds that a former 357 can eat all day long and have been stacking up well against most .40S&W.
 
Jim March said:
* Reloading is faster and extraction is faster - DA or SA. On a DA you can use moons. On an SA you can thumb rounds into the loading gate out of 1911 mags or the like - not exactly "the cowboy way" but it works. And the tapered rounds extract faster and more reliably.
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I wouldn't bet on that one. It's so little taper it almost doesn't count: .0028" for the body of the case.

http://www.saami.org/PubResources/CC_Drawings/Pistol/45 Automatic.pdf

Yes, it's a taper, but so minor that you can't see it with the nekked eye. The 9mm Parabellum has a considerably more pronounced taper to it.
 
Ah. Whoops. I thought the 45 taper would be more pronounced.

Still, when we're talking about cramming one cylinder into another, even miniscule tapers might help.

I know that 9mmPara shells auto-eject from Maurice much, MUCH harder than longer taperless 357Magnum shells. The difference shocked me, I had to add a hammer-mounted shell deflector immediately following my first shooting test in 9mm. 357s had been harmlessly bouncing off my goatee under gas-powered ejection straight back.

9mm standard pressure was thwacking my cheekbone.
 
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