Can 45 Acp single action revolver cylinders be reamed to 45 Colt? If not, why?

It should be able to, but depending on brand of the ACP cylinder, some are very hard to get ahold of, whereas the 45 Colt are common. Might think of picking up a spare cylinder in 45 Colt. IMO, the best way to get a very accurate 45 Colt is to start with a 357 cylinder and have it rebored. That way you make sure you get the proper diameter throats. I have seen some of the ACP cylinders, especially on the Italian guns that have the wrong throat diameter.

Sorry, Mike. I should have been more specific in my post. I am most interested in dual cylinder Ruger Blackhawk and vaquero 45 acp cylinders. It would be nice to have the factory 45 Colt cylinder with .4525" throats, for modern .452" cast bullet designs, and the second cylinder in 45 Colt with .454-.455" throats, for older designs like Lyman #454190 and RCBS 45-270SAA. Having to size down cast bullets .002", or more, is often a detriment to accuracy. I like to resize cast bullets as little as possible, and prefer to not shrink them at all. Thank

With modern powders, in your Ruger, you'd both easily and safely be able to duplicate any factory .45 Colt loading using, I'd suggest, .45 Auto Rim cases for safety as I don't think such loadings would be safe in any .45 ACP 1911 style pistol.

But regarding the re-sizing issue I don't think that sizing down by .002" in a Ruger Vaquero is not going to have any real worl accuracy difference. Even out to fifty or seventy-five yards.

My input, without meaning to be be rude, is that you are seeking an expensive answer to a non existent problem given the weapon you are using AND EASILY SOLVED WITH A DECENT CAST BULLET SIZING DIE. And that may be the easiest answer.

My 45 LC Ruger cylinder throats measure .452. And so does the barrel. Make sure you aren't chasing smoke.

quote:

Originally posted by enfieldspares:
With modern powders, in your Ruger, you'd both easily and safely be able to duplicate any factory .45 Colt loading using, I'd suggest, .45 Auto Rim cases for safety as I don't think such loadings would be safe in any .45 ACP 1911 style pistol.

But regarding the re-sizing issue I don't think that sizing down by .002" in a Ruger Vaquero is not going to have any real worl accuracy difference. Even out to fifty or seventy-five yards.

My input, without meaning to be be rude, is that you are seeking an expensive answer to a non existent problem given the weapon you are using AND EASILY SOLVED WITH A DECENT CAST BULLET SIZING DIE. And that may be the easiest answer.

Enfieldspares,

Thanks for your opinion. I did not think you are being rude, just giving your honest opinion. Nothing wrong with that. I've been casting for, loading, and shooting 45 colt loads in several different 45 colt revolvers for 20 years. Throat diameters have varied from .448" to .458". Sometimes sizing bullets down doesn't appreciably affect accuracy, and sometimes it does. It depends on the cast bullet alloy (i.e. Bullet hardness), the lube groove depth (Lyman #454190 has pretty shallow radius-bottomed grooves), whether you are sizing bottom-to-top or top-to-bottom, velocity, pressure, and what your particular gun seems to tolerate. I have sometimes noticed some pretty big accuracy differences in sized down bullets, and have noticed best accuracy with non-sized bullets that properly fit chamber throats, even if they are getting squeezed down a few thousandths of an inch when hitting the forcing cone of the barrel. Your personal experience may be different than mine, but I'm gonna stick with what I've found works best for me, and a dual cylinder gun in 45 colt with .4525" and ".455" throated cylinders sounds pretty sweet.

quote:

Originally posted by dpcd:
My 45 LC Ruger cylinder throats measure .452. And so does the barrel. Make sure you aren't chasing smoke.

You are pretty lucky then. My first couple Blackhawks measured .448". I had them honed to .4525". I had an early 70's New model that went .458".

I have seen many switch barrel such guns..Its .452 as opposed to 454 as I recall, that seems to be close enough..And some factories have done so..I have seen a few early S&W that shot both with different cylinders, I assumed at the time they were factory, but wouldn't swear to that..Never was anything that interested me much.

You need to check the headspace (the space between the recoil shield and back of the cylinder) that is the space for the rim of the cartridge. If it's too large you'll get mis-fires as the energy from the firing pin is shoving the cartridge forward instead of crushing the primer.
I don't know if Ruger cut their chambers to allow the use of the 45 Auto Rimmed cartridge as well as normal 45 ACP, if they did then you won't be able to re-chamber to 45 Colt as there will just be way too much headspace.