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.45 Auto Rim vs. .45 Cowboy Special


Black Angus McPherson

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I was in one of the local gun stores a couple weeks back and saw some .45 Auto Rim cases for sale.  It got me to wondering:  What's the difference between the .45 AR and the .45 CS?  They look pretty close and the Auto Rim seems a lot easier to come by.

 

What say you folks that are in the know?  Are they essentially interchangeable?  Could one use the same load data used for the .45 CS and use them for CAS?

 

I didn't buy any to experiment with, it just got me curious.  Besides, I don't have any real need for either .45 CS or .45 AR.

 

Angus

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Could one use the same load data used for the .45 CS and use them for CAS?

 

Let me rephrase that question - would .45 AR cases be safe to use in revolvers that were chambered for .45 AR with loads using C45S data?  

 

Yes, if the C45S loads are safely researched and kept to the pressure limits that .45 Colt uses (see below), they would generally be safe, because the pressure limits for .45 AR are about 4000 psi higher than general purpose .45 Colt load pressures, which has been adopted for lack of a SAAMI standard for general purpose C45S loads, too.  Many sets of loading data I have seen for C45S fail to meet the carefully researched criteria, however.   

 

Loading data for the AutoRim may exceed pressures that the .45 Colt revolvers can safely handle.    Although the case internal dimensions are essentially the same for all three related cartridges (.45 auto, .45 auto rim, Cowboy .45 Special) - the max pressure specs that the firearm in which they are intended to be used are quite a bit different.

 

.45 auto has the highest    21,000 PSI

.45 auto rim lower               18,000 PSI

 

.45 Colt, which is what the Cowboy .45 Special fits into, has the lowest.     14,000 PSI   !

 

Cowboy .45 Special loading data has to be worked up by a knowledgeable experienced loader, as NO commercial data is available (or probably will ever be available).   It's like a wildcat rifle cartridge.  There is no SAAMI specification for C45S ammo.  The safest thing we can do is respect the low pressure limits that the weakest of the .45 Colt revolvers handle safely.

 

Fortunately, for Cowboy ammo loading, making 750 FPS or so loads, that is not too tough a challenge.

 

 

Yes, I know that Ruger has made interchangeable cylinders for Blackhawks and old model Vaqueros, one each in .45 Colt and .45 auto.  I've even got a Blackhawk chambered like that.  But that is on the Blackhawk size frame, which is good for .44 Magnum pressures (in the correct cylinder)!

 

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They look pretty close

 

Really?  Not close enough for Cowboy work.  :o  Or any other revolver usage.

 

Good luck, GJ

 

 

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11 minutes ago, Irish-Pat said:

The rim is too thick to use in our single actions on the 45 auto rim.

 Yep, what he said. They would work if you have a 45 ACP cylinder, or you thin the rims a tad.

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I bought a 100 Autorim cases and tried to cut some off the back side of the rim to make C45S cases.  I couldn't come up with a good way to chuck the case in the lathe and then cut a consistent amount off the back of rim.  I ended up loading the balance as 45 Autorim and giving them to my son to shoot in an old Webley that had been "shaved" to use 45ACP with clips or 45AR. 

 

If you're coming to our match in September,  remind me and I'll bring some brass and we'll talk loads. 

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7 minutes ago, Warden Callaway said:

I bought a 100 Autorim cases and tried to cut some off the back side of the rim to make C45S cases.  I couldn't come up with a good way to chuck the case in the lathe and then cut a consistent amount off the back of rim.  I ended up loading the balance as 45 Autorim and giving them to my son to shoot in an old Webley that had been "shaved" to use 45ACP with clips or 45AR. 

 

It is a good bit easier to cut 45 long colt cases to the length of 45CS cases than to thin out the auto rims.

I have read where people claim that the 45LC cases are thicker towards the base of the case and that it causes problems with bullet seating. I have not found any difference  in wall thickness to back that claim up. I regularly have taken my split 45LC cases and shortened them and they end up mixed in with the 45CS brass I bought. No problems at any stage of the reloading process or any difference in performance when I shoot them. I use Starline 45LC brass exclusively so if people are finding wall thickness differences, maybe its with a different brand of brass.

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51 minutes ago, Irish-Pat said:

The rim is too thick to use in our single actions on the 45 auto rim.

45 Auto Rim ........ 0.083 rim thickness+-

45 Colt...................0.060 rim thickness+-

Having cut down hundreds of 45 Colt cases, it's not that hard to make C45S! ;) As already stated above, Auto Rim isn't worth the effort to try and modify to create C45S.

 

15 minutes ago, Mossy Pops said:

 

It is a good bit easier to cut 45 long colt cases to the length of 45CS cases than to thin out the auto rims.

I have read where people claim that the 45LC cases are thicker towards the base of the case and that it causes problems with bullet seating. I have not found any difference  in wall thickness to back that claim up. I regularly have taken my split 45LC cases and shortened them and they end up mixed in with the 45CS brass I bought. No problems at any stage of the reloading process or any difference in performance when I shoot them. I use Starline 45LC brass exclusively so if people are finding wall thickness differences, maybe its with a different brand of brass.

Having also bought several thousand cases since Adirondack Jack developed C45S, you will not see any difference in loading cut down or factory cases at CAS velocity levels IMHO! 

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45 autorim cases were developed for use in WW2 revolvers, as I recall. Really can't see how the loads would be too hot for our modern cowboy revolvers. When I wanted a load for my wife using the 45CS cases, looking up 45 AR loads was exactly where I went, and it has worked fine so far.  Just use the lower loads. If you use Trailboss I can tell you what I have been using,  just shoot me a pm. You can also use the lower 45 Schofield loads to get close. Trailboss is pretty forgiving.

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12 minutes ago, Captain Clark said:

(After having) bought several thousand cases since Adirondack Jack developed C45S, (I have not) not seen any difference in loading cut down or factory cases at CAS velocity levels IMHO! 

 

 

In fact, I get MUCH better life with exactly the same ability to load slugs up to 200 grains in cut down .45 Colt cases as I do with the Starline-made Cowboy .45 Special cases.  I load both interchangeably with the same loads, and same dies.   Cracked cases occur in that mixed batch almost 100% from the commercially made C45S headstamps, and very few from the R-P, CBC, PMC and other "junker" headstamps that I cut down from .45 Colt.  I'll never worry that I need to buy commercial C45S cases again.  They are expensive (relatively speaking) and short lived.

 

Good luck, GJ

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1 hour ago, Garrison Joe, SASS #60708 said:

 

Loading data for the AutoRim may exceed pressures that the .45 Colt revolvers can safely handle.    Although the case internal dimensions are essentially the same for all three related cartridges (.45 auto, .45 auto rim, Cowboy .45 Special) - the max pressure specs that the firearm in which they are intended to be used are quite a bit different.

 

.45 auto has the highest    21,000 PSI

.45 auto rim lower               18,000 PSI

 

.45 Colt, which is what the Cowboy .45 Special fits into, has the lowest.     14,000 PSI   !

 

Cowboy .45 Special loading data has to be worked up by a knowledgeable experienced loader, as NO commercial data is available (or probably will ever be available).   It's like a wildcat rifle cartridge.  There is no SAAMI specification for C45S ammo.  The safest thing we can do is respect the low pressure limits that the weakest of the .45 Colt revolvers handle safely.

 

Fortunately, for Cowboy ammo loading, making 750 FPS or so loads, that is not too tough a challenge.

 

 

Yes, I know that Ruger has made interchangeable cylinders for Blackhawks and old model Vaqueros, one each in .45 Colt and .45 auto.  I've even got a Blackhawk chambered like that.  But that is on the Blackhawk size frame, which is good for .44 Magnum pressures (in the correct cylinder)!

 

 

Really?  Not close enough for Cowboy work.  :o  Or any other revolver usage.

 

Good luck, GJ

 

 

 

Interesting info.  I wouldn't be concerned about .45 ACP or .45 AR SAAMI pressures as I would be using C45S (Thanks for correcting my nomenclature) load data.  IIRC the C45S was originally designed with the idea that it would be used for Black Powder loads to cut down on the large amounts of BP needed in  a .45 Colt case.  And, of course, the recoil that comes with those loads.

 

So, if I understand this correctly, IF someone were to give me a large pile of .45 AR cases and I wanted to use them for CAS I could do so by reducing the thickness (not the diameter) of the rim and using an appropriate C45S load.  I think that pretty well answers my question.

 

All in all I agree that it would probably be easier to cut down some .45 Colt cases.

 

Thanks,

 

Angus

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Reducing rim thickness isn't the only problem, But I believe you would have to cut the primer pocket the same amount you reduce rim thickness.  - roughly .023        GW

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1 hour ago, Warden Callaway said:

I bought a 100 Autorim cases and tried to cut some off the back side of the rim to make C45S cases.  I couldn't come up with a good way to chuck the case in the lathe and then cut a consistent amount off the back of rim.  I ended up loading the balance as 45 Autorim and giving them to my son to shoot in an old Webley that had been "shaved" to use 45ACP with clips or 45AR. 

 

If you're coming to our match in September,  remind me and I'll bring some brass and we'll talk loads. 

 

I'm not sure if I'll be there next month.  September is looking to be a pretty busy month.  Plus, my shotgun broke during the last stage of the last match.  The left hammer won't stay cocked and I don't know, yet, if the sear broke or if there is some other problem.  It's an TTN/Cimmaron 1878 Colt copy.  

 

Angus

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Howdy

 

The Smith and Wesson, and Colt model 1917 revolvers were chambered for the 45 ACP cartridge. In order for the extractor of these revolvers to eject empty cartridges, they were placed on half moon clips. That way the extractor could engage the half moon clip. The S&W Model 1917, as shown below, can fire 45 ACP without clips as the cartridge headspaces on the case mouth, but you need a stick to poke out the empties.

 

Because of the arrangement of the clips and cartridges, there was about an extra .030 of space between the rear of the cylinder and the frame. This was for the thickness of the clips. A lot of these revolvers became available after WWI, and Remington developed the 45AR cartridge with an extra thick rim (about .090 vs about .060 for 45 Colt). This meant the revolvers could be loaded without clips and the extractor could engage the rim of the cartridge.

 

 

1917andammo.jpg

 

 

 

 

The cartridges in this photo, from left to right, are 45 Colt, 45 Schofield, 45 Cowboy Special, 45 Auto Rim, and 45 ACP. It is obvious in this photo how much thicker the rim is on the 45 AR than any of the other cartridges. The extra .030 of rim thickness prevents the cartridge from seating all the way in a revolver chambered for 45 Colt.

 

45C45Sc45CowboySP45AR45ACP.jpg

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 Send me your 45 auto rim  brass and I will swap you some 45 Long colt brass for them.  I still shoot my granddaddy's S&W 1917 from WWI and whiskey running days. Irish Pat

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25 minutes ago, G W Wade said:

Reducing rim thickness isn't the only problem, But I believe you would have to cut the primer pocket the same amount you reduce rim thickness.  - roughly .023        GW

If you were to reduce the rim thickness, you'd do it from the front side of the rim. Not the headstamp side. You would not want to cut the primer pocket .023 deeper.

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3 hours ago, Garrison Joe, SASS #60708 said:

...Yes, I know that Ruger has made interchangeable cylinders for Blackhawks and old model Vaqueros, one each in .45 Colt and .45 auto.  I've even got a Blackhawk chambered like that.  But that is on the Blackhawk size frame, which is good for .44 Magnum pressures (in the correct cylinder)!...

 

Uberti makes their SAA guns with convertible .45 Colt / ACP cylinders as well, so it must handle the pressure.  Actually, if a shooter had a .45 Uberti clone, he could fit an ACP cylinder to it and use plentiful ACP brass.

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   3 hours ago,  Garrison Joe, SASS #60708 said: 

...Yes, I know that Ruger has made interchangeable cylinders for Blackhawks and old model Vaqueros, one each in .45 Colt and .45 auto.  I've even got a Blackhawk chambered like that.  But that is on the Blackhawk size frame, which is good for .44 Magnum pressures (in the correct cylinder)!...

The Ruger New Vaquero is offered in .45 ACP and it is not on the .44 Magnum frame.

 

http://www.ruger.com/products/vaqueroBlued/specSheets/5154.html

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We must remember that 45 ACP is not legal in Classic Cowboy / Cowgirl categories. You must use RIMMED ammunition, { PG 13} ROI

All other age, style, etc categories, 45 ACP is quite acceptable!:)

 

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1 hour ago, Boggus Deal #64218 said:

If you were to reduce the rim thickness, you'd do it from the front side of the rim. Not the headstamp side. You would not want to cut the primer pocket .023 deeper.

Thanks

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Howdy- Driftwood's post with that great pic of different .45 rounds lined up brought back into the light an alternative  to the whole have a cylinder trimmed for Auto Rim vs. C45S. It USED to be common practice to simply use .45 Schofield brass as MOST of our guns will accept them ( the rim IS a bit larger than that found on .45 Colt brass ). I struggled with inconsistant "light" loads in .45 Colt brass before finally buying Schofield brass from Starline. N ow I save the "long" brass for my rifle, and non CAS use.

Jus' sayin"

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21 minutes ago, Conestoga Smith, SASS #18219 said:

Howdy- Driftwood's post with that great pic of different .45 rounds lined up brought back into the light an alternative  to the whole have a cylinder trimmed for Auto Rim vs. C45S. It USED to be common practice to simply use .45 Schofield brass as MOST of our guns will accept them ( the rim IS a bit larger than that found on .45 Colt brass ). I struggled with inconsistant "light" loads in .45 Colt brass before finally buying Schofield brass from Starline. N ow I save the "long" brass for my rifle, and non CAS use.

Jus' sayin"

.45 Schofield rims are slightly larger in diameter than a .45 Colt.  The .45 AR rim is THICKER.  It will not fit in any gun chambered for .45 Colt.

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??? Was there some question as to that in my post ? I never said the AR would fit w/o modification to an ACP cylinder. Never said the AR would fit in any gun chambered for .45 Colt.  Seems to not be a question anywhere in the thread that .45AR brass has a thicker rim. Just pointing out an alternative to paying for machine work on .45 ACP  cylinders or paying for proprietary brass, well executed though it is.  As for the rim being bigger ( larger diameter ) on Schofield brass, yeah, I said that, too.

 

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ive only used the 45AR in my webleys that is a light load similar to the cowboy loads of about 650fps but as stated the rim thickness always kept me shootin 45LC in my cowboy guns - that and wanting one load for revolvers and rifle standardized 

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15 hours ago, Black Angus McPherson said:

IIRC the C45S was originally designed with the idea that it would be used for Black Powder loads to cut down on the large amounts of BP needed in  a .45 Colt case.

Not so exactly but it certainly did cut down on the amount of BP consumed.

 

When AJ received his first batch of cases from Starline,he went to work testing with just about every 45 ACP load in them with a large variety of bullet weights.

 

Then he tested combinations of BP which is rather simplified with varying bullet weights including the Big Lube bullets.

 

His next step was to have a custom mould produced for his 125 gr. Barnstormer bullet for use with smokeless as it wouldn't because of design carry enough lube for BP use.

That is a quick breakdown on AJ's development of his Cowboy 45 Special as a cartridge.

 

If anyone has any interest in his Barnstormer bullet mould for use in a Master Caster,he has it available as his health precludes it's use.            Adios   Sgt. Jake

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17 hours ago, Black Angus McPherson said:

 

I'm not sure if I'll be there next month.  September is looking to be a pretty busy month.  Plus, my shotgun broke during the last stage of the last match.  The left hammer won't stay cocked and I don't know, yet, if the sear broke or if there is some other problem.  It's an TTN/Cimmaron 1878 Colt copy.  

 

Angus

Howdy Angus, mine did that.  It was a small spring for the sear.

 

 

 

 

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Another interesting bit of trivia is that if you have a .45 ACP cylinder for your Colt SAA, they will not chamber .45 Autorim.  They didn't make the cap between the frame and the cylinder big enough.  The ACP's sit quite deeply into to the chambers.

 

Kind of a bummer IMO.

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2 hours ago, H. K. Uriah, SASS #74619 said:

Another interesting bit of trivia is that if you have a .45 ACP cylinder for your Colt SAA, they will not chamber .45 Autorim.  They didn't make the cap between the frame and the cylinder big enough.  The ACP's sit quite deeply into to the chambers.

 

Kind of a bummer IMO.

 

Same with the Rugers I had in 45ACP.   But I could shoot C45S if I loaded them with 451 bullets and used ACP  dies.

H

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Perhaps this is the obvious,with the Cowboy 45 Special there is no need for 45 Auto Rim. I just wish they were as available as when Adirondack Jack had the rights but if wishes were fishes.                     Adios   Sgt. Jake

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My 2 cent's worth. I stole a SAA because the previous owner had shot up all of his granddaddy's bullets and the gun shop couldn't I.D. the 1 remaining cartridge. Knowing that I could have it reamed to Schofield or 45C, I bought it for a cheap trade. A trip to CARTRIDGES OF THE WORLD  with a micrometer showed that it used 455 ELEY or 455 COLT cartridges. BUFFALO ARMS sent me 1000 cases made from shortened AND THINNED  45 Colt cases. I cut and trimmed my own 45C cases, but the cases were too thick at the mouth after shortening. My load is the SAFE load I use in all my 45ACP SAAs, both black and smokeless frames. The pressures are rediculously low with my favorite shotgun powder. 455 and 45ACP target loads are essentially the same AND shoot well in my 45 Colt cylinders in my BP TIGHT SAAs; best to use later 455 or 45ACP cylinders. Hope this helps. Dirty Doc. mzac28717@aol.com, 828-743-2114

 

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1 hour ago, Ranger Sgt. Jake McCandless #3368 said:

Perhaps this is the obvious,with the Cowboy 45 Special there is no need for 45 Auto Rim. I just wish they were as available as when Adirondack Jack had the rights but if wishes were fishes.                     Adios   Sgt. Jake

 

Actually, the Sergeant is correct.   There is no real need for the .45AR in a SASS context.   The only reason why I wish that the AR would fit in a .45ACP cylinder is because I have several 1917's and Webley's that I use the AR's in.   It would be nice to be able to use them in the SAA as well when I go "old time revolver shooting" with some friends and only need to take 1 caliber of ammunition.

 

But I an weird.

 

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HK: Lathe some off the back of the cylinder like was done to too many Webleys and you can have your wish.

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On ‎8‎/‎17‎/‎2017 at 0:17 PM, Irish-Pat said:

The rim is too thick to use in our single actions on the 45 auto rim.

I shoot .45 auto rim in my Colts. I'll try to corner gun/bullet boy to answer your questions. All I can say is that I can't tell any difference in recoil between them and the .38s I shot until I ran out of ammo.

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2 hours ago, Allie Mo, SASS No. 25217 said:

I shoot .45 auto rim in my Colts. I'll try to corner gun/bullet boy to answer your questions. All I can say is that I can't tell any difference in recoil between them and the .38s I shot until I ran out of ammo.

Allie are you SURE you are shooting Auto Rims?  A .45 Auto Rim will NOT fit in a Colt single action unless it has been modified.

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6 minutes ago, Larsen E. Pettifogger, SASS #32933 said:

Allie are you SURE you are shooting Auto Rims?  A .45 Auto Rim will NOT fit in a Colt single action unless it has been modified.

Yep! They are such cute little shorties.;)

 

Hubby has a metal lathe so he may have done the modifications.

 

I asked him about the OP's questions and he rambled about crimping and accuracy. He did not recognize the term "Cowboy Special." Does that help?

 

He shot them before he quit shooting in 2005. He was very accurate and what used to be considered fast :lol: for a duelist.

 

Maybe I'll take photos.

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