ruger .45acp cylinder to .45AR

Does anyone know how much you would have to machine off the rear of a ruger blackhawk .45 acp cylinder so it would accept .45AR? It shouldn't affect the use of .45acp, due to head spacing on the case mouth.

I was going to look for a Ruger forum, but I thought I would have better luck starting with people that would be more familiar with .45 auto rim.

There was an magazine article about the gun I have, and the author talked about doing this, but I can't remember where I read it.

Any help would be great, thanks

I've had the same thought about altering the Ruger cylinder. Have you checked whether the rims will clear the cyl. ratchet without mods?

Larry

No I didn't, never thought about that. The .45 colt rim can't be that much smaller than .45AR. I'll have to check that when I get home from work tonight.

lebomm said:

I've had the same thought about altering the Ruger cylinder. Have you checked whether the rims will clear the cyl. ratchet without mods?

Larry

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The diameter of the rim of an .45 Auto Rim cartridge wasn't an issue, at least in MY New Model Blackhawk. I had a friend, who owned a lathe, shave my .45 ACP cylinder to also accept .45 Auto Rim.

Do you recall how much was removed from the back of the cylinder? I'm having it done by the machienist at work, and I can't take the gun in to work with me for a trial and error fit check.

You can figure it out with feeler gauges. Your A,B measurements need to be made at the firing pin..

A: You need the distance between the frame and the heel of a .45acp when in the cylinder.

B: You need the distance from the cylinder to the frame with no case.

C: you need the thickness of a .45ar rim.

B-A=?

C-?= the amount you need to cut off....

Make sense?

But why would anyone want to go to the trouble of doing this? .45 ACP brass is much more available and far cheaper than .45 AR, and with a single action Blackhawk, there is no difference in loading and unloading between the two cartridges. Seems to me to be an excellent way to waste time and money with nothing to gain, unless you have a considerable quantity of .45 AR ammo laying around.

I’ve shot with owners of .45 convertible Black Hawks (BHs) that were machined to also fire .45 AR. If I owned a large frame .45 BH I’d have the ACP cylinder modified because I reload .45 AR and the only disadvantage I can think of would be possible loss of collector value which isn’t an issue with most new model BHs.
For the dimension the O.P. wants why not visit the Small Arms and Ammunition Manufactures Institute (SAAMI) and get min. & Max. .45 AR head space specifications. The rest would be feller gauge measurements and arithmetic. SAAMI

You'll be removing the AR rim thickness from the rear of the cylinder.
The OAL of the two rounds is the same.
The headspace is already established in the revolver between the 45acp case mouth edge in the chamber(s) and the breech face of the frame.
You are just making space for the rim,,nothing else,,no additional case length.
BUT do check with the SAAMI specs and do a carefull job of it. Many 455 Webley revolvers were converted by turning the rear of the cylinder off and many are way off as far as headspace.
They work,,but why not do it safely & correctly.

The 45AR does allow you to crimp bullets into place if that satisfies any of your reloads needs. The 45acp needs the case mouth square and uncrimped to headspace on. A small thing, but it can make a difference in some loads and performance.
,,,and I just like the looks of the case rims showing personally!.
A 3 screw 357 w/ nasty scope mt holes in it awaits conversion...

But I still have to ask the question - why bother??? I know some people just can't resist screwing around with their guns, and I suppose that must be the reason.

DWalt said:

But I still have to ask the question - why bother??? I know some people just can't resist screwing around with their guns, and I suppose that must be the reason.

Click to expand...

Since I started this thread, I'll answer your question.
You were correct on all counts. I have 500 rounds of .45AR that I already reload for my .45acp S&W revolvers, and yes, it is the irresistable urge to make things better, when I preceive a problem.
Looks like I'm going to need to do some measureing and some math. I was just hoping someone had tried this already.

target tech said:

[...] Looks like I'm going to need to do some measureing and some math. I was just hoping someone had tried this already.

Click to expand...

Yup. The way you posed your question presumes Ruger would waste time and money holding a non-critical dimension to tolerances as tight as needed for head space. I don't know if they do or not, but the gap behind a .45 ACP only cylinder could vary quite a bit and make no difference while firing the revolver. Even if Ruger held that gap to tight tolerances, the tolerances you give to your machinist co-worker get add together with Ruger's probably accumulating to a wider range than is allowable for head space. I would rather see you spend a little time and be sure you get your head space correct.

The easiest way to determine the amount to remove would be to insert a .45 ACP round into a chamber, and measure the the head protrusion from the face of the cylinder. Use several rounds and several chambers and take the minimum. Then measure the thickness of the .45 AR case rim, which should be about 0.09" Again, measure several rims and use the thickest measurement. Subtract the fomer from the latter, and that should be the amount required to machine down the cylinder face.

By the way, I checked SAAMI spec drawings, and the .45 AR rim thickness tolerance range is 0.079" to 0.089" Therefore, just use 0.089" as the rim thickness in your calculation, as it should be the worst-case condition. I would have no idea what the protrusion of the .45 ACP head would be, as that measurement would be specific to Ruger. You'll have to measure that to get a good idea of a minimum value. A dial caliper should work, but a hole depth micrometer would be better.

Here's the best Ruger Forum:
RugerForum.com • Index page

There have been several threads about this very minor but very useful modification. Some will always ask why do it? And the shortest answer is the proverbial: if you have to ask the question you won't understand the answer anyway.

So you needn't try to answer.

The short answer is 'face off' .089". ACP rounds do not protrude from the Ruger cylinder. But, nothing is ever "never" or "always" in this world.

So double check yours with the cylinder out of the gun and a straight edge using factory ammo (different brands) just to be sure, and check every chamber with several different rounds.

If you have protrusion and it's the same or within a few .001"on all 6 chambers don't worry about it if the cylinder has been shot w/o problems. Just use a caliper to measure the cylinder length with the longest rounds chambered and without. The difference in those two measurements is how much to SUBTRACT from the .089" cut.

Just for kicks let's say the protrusion differs from chamber to chamber by more than a few .001"; it should go back to Ruger to have the shoulders equalized under warranty unless whoever is facing off your cylinder can do it.

There’s more: in addition to your question, there has been discussion about using full moon clips in a Ruger. Yes of course you must remove and replace the cylinder to use them, so why you may ask. Well it might be counterintuitive but many, many SA handgunners use SAs for concealed carry and backup carry while hunting.

And everyone knows a SA reload is the slowest of any handgun. But there is no faster reload in a SA than a cylinder swap or speed load by removing cylinder, reloading with a another loaded cylinder with rounds in a full moon clip (or dumping 6 cases in a full moon clip and speed load the original cyl with 6 clipped rounds ala Jerry Miculek) and popping the cylinder back in. For the average person it's about twice as quick or quicker with just a little practice.

You can shoot the 45 Colt cylinder first and your ACP cylinder can be your backup cylinder fully loaded with 6 clipped rounds of ACP. The clip is a real benefit to prevent errant loose rounds from dropping out of the cyl while replacing it in the gun. That scenario is why the ACP cylinder should be the backup load.

So where do you get full moon clips for a Ruger? You can’t, but Smith moon clips are extremely simple to modify whether you have a mid frame Flat top Blackhawk (and New Vaquero) or the full size Blackhawk. But both chamber centerline-to-axis centerline radiuses are smaller than the S&W N frame cylinder. That’s a good thing because the moon clips load from the outside and can be fitted. First with a Dremel tool, slightly round out the center hole until it slips over the ratchet hub of the Ruger cylinder. Lastly deepen the notch for each round; slightly for the large frame Blackhawk and just a little more for the mid-frame cylinder until a loaded clip plops onto the cylinder with no binding of the rounds as they drop into the chambers and your done!

While you’re facing off the ACP cylinder, think about facing off .044” from the 45 Colt cylinder as well (.045” less than the ACP cyl) and shoot ACP clipped rounds in it as well as 45 Colt! Or for $80 Mark at Pinnacle Guns will alter the cylinder for moonclips so you can shoot .45 ACP through it, and keep the .45 Colt capability.
http://www.rugerforum.com/phpBB/viewtopic.php?t=147059

Note: by surface grinding .020” off of a standard steel moon clip (with the above fitting) you can actually shoot ACP in an unmodified 45 Colt cylinder.

Now this may not matter at all to you, and you can just enjoy shooting the 45 AR, but the additional versatility is still there.

I know that’s a lot more than you wanted to know but I hope it helps and all the best in your endeavor,

I know full moon clips are all the rage now but I would not turn my cylinders down to accept moon clips unless you are a competition shooter and every mili-second counts.

For the 45 acp cylinder. I would not "shave" the back off. I would have each chamber counter sunk the correct depth to accept the 45AR cart. That way if a case ruptures it is contained rather than blowing all over the place. Before you say how often does a case rupture? You wear eye protection don't you for just such a incident?

Just my 2 cents.

John

jspick said:

I know full moon clips are all the rage now but I would not turn my cylinders down to accept moon clips unless you are a competition shooter and every mili-second counts.

For the 45 acp cylinder. I would not "shave" the back off. I would have each chamber counter sunk the correct depth to accept the 45AR cart. That way if a case ruptures it is contained rather than blowing all over the place. Before you say how often does a case rupture? You wear eye protection don't you for just such a incident?

Just my 2 cents.

John

Click to expand...

John,

That's at least $10 worth.
Personally I don't like messing with 1/2 or full moon clips. And since the OP was only interested in being able to shoot 45 AR in his Ruger ACP cylinder, your recessed chamber suggestion is a most excellent one, especially for him.

But IIRC he wanted to be able to see the rims from the side.
And case head blowouts in centerfire cartridges with their solid head cases is a thing of the past with the old balloon head cases as evidenced by the way all ACP cases are unsupported in modern DA cylinders which are all cut for clips. And the ACP case rims in the recessed Ruger chambers would then no longer be tightly surrounded either.

But I would still opt for your recessed chambers idea and it's also a great idea to be able to shoot 45 AR in 45 Colt cylinders as well!

This thread reminds me of that old Red Green sating "If it ain't broke-you're not tryin' hard enough."

Ruger has in general very tight chambers on the 45 acp cylinders. If you were to get the cylinder recessed, you should also have the chambers rethroated and uniformed. Neither of my Blackhawks will chamber ammo that flows through my Kimber.
The 45 acp is also generally the most accurate of the two cylinders by far. I would not change it for that reason.

The late Skeeter Skelton discussed modifying the .45 ACP cylinder of a convertible Colt SAA to use .45 Auto Rim. This was in one of his Q&A columns in Shooting Times magazine. He planned on counterboring the rear of each chamber to contain the rims, as opposed to refacing the entire rear of the cylinder as is being discussed here. He wrote that being able to shoot all three of the major .45 caliber handgun rounds would be "guilding the lily." But then he went on to write that he hadn't gotten around to it and likely never would, as at the time he wrote this (the late 1970's, I believe), .45 Auto Rim ammo was seldom encountered, which at that time was true. He never envisioned the flowering of popularity of .45 ACP revolvers we have seen in the last 20 years, which drove the broad use of the .45 Auto Rim cartridge of today.