I have a model 25 that I shoot 45 ACP in. I was getting tired of loading and unloading the moon clips, so I bought a bunch of 45 Auto Rim brass. I was surprised when I looked up the loads for those in my Lyman manual to find that the loads are a good bit reduced in comparison to 45 ACP. I would have thought they would be identical.

Max loads for 45 ACP 45 Auto Rim
200 gr LSWC

Bullseye 5.6 4.7
231 6.0 5.5
Unique 7.5 6.8

Is the 45 Auto Rim brass that different from 45 ACP brass? I thought they were identical except for the rim. Anyone know why the different loads?

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What could possibly go wrong?

I have used the exact same data for 45 AR as my 45 ACP for many years....other will chime in shortly many with the same results.

Randy

I do the same. I load my .45 AR and .45 ACP exactly the same. Never had a problem. I shoot them in a model 1917 and a model 625. I load 4.8 gr of Bullseye and a 230 gr Berry's Bullet.

The “reduced” loads were because the AR was loaded with lead bullets and the S&W rifling was, supposedly, not compatible with lead bullets only jacketed. It has been proven countless times, that with correct alloys and proper sizing, lead bullets are superb in ACP revolvers.

Kevin

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Unshared knowledge is wasted.

I used to shoot AR brass in my 25 using moderate .45 ACP loads and never experienced a problem. Important not to be using any of the old “balloon head” brass. A problem I had to pay special attention to was not using the AR ammo loaded for my 25 in my shaved Webley MkVI and S&W 1917. Sadly the model 25 and 1917 is gone so that is no longer an issue.

You may find this 'Pet Loads' article helpful. https://www.handloadermagazine.com/45-auto-rim-p

I don't know anything about loading for Webleys, but any S&W or Colt .45 ACP /.45 Auto Rim revolver in good, tight condition should be fine for using regular .45 ACP data. However, I wouldn't use any hot .45 data in a one hundred year-old S&W or Colt.

The interior case dimensions/capacity isn't the same due to the AR case not having an extraction groove. That may be why the same load will cause some variance in velocity and pressure testing which might be reflected in the load data.

Not something I would worry about.

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That's just somebody talkin.

I have a Speer #3 and a Speer #7 reloading book and they spend a bit of time discussing the "balloon" or "folded head" AR case. I think it would be a bit of a challenge to find those cases still around, but one never knows. I would think any regular 45 ACP load would be fine in modern 45 AR brass in a modern gun. I think I'd stay away from anything close to ACP max in an older revolver using unknown AR brass.

I use Starline .45 AR brass in my 625's and 1955 Target. Excellent quality and internal capacity is the same as their .45 ACP cases. No problems whatsoever using .45 ACP load data in the AR case in a modern revolver such as the OP's Model 25. As always, start low and work up to your desired load level.

I just started loading AR cases about a year ago. Like you, I noticed a difference in load data between he AR and the auto cases. I had always been told you can load them the same. However, the loading manuals did not agree with that assumption. I treat them as different cases, and stay with the loading manuals info. However, if you stay under max loads, and within the limits on both, you could load the same powder charge without issue.

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Richard Gillespie
FBINA 102

FWIW, I have a 1917 that is much more accurate with AR than ACP. I load the AR cases using the standard ACP hardball loads and Berry’s 230 plated bullets. I’ve had no problems with my 1917.

I might opine that any balloon head auto-rim brass you find might be better directed to an antique cartridge collector rather than reloaded...?

The Starline product is every bit as robust as a 45 acp and I believe they actually state is constructed with the "same integrity as our 45 Colt case"...

This would, I believe, preclude worries about any balloon head pressure concerns?

I use regular 45 acp load data all the time: Buffalo Bore loads three for this caliber and, in addition, three in 45 Auto Rim +P!

Cheers!

P.S. They also state this will not harm any "post War" 45 acp revolvers as well.

P.P.S. They ALSO state their 45 Colt brass is "tested to 44 Magnum pressures" which leads me to believe their 45 Auto Rim brass is pretty durn stout as well (because if a is > or = to b, and b is > or = to c, then a is at LEAST = to c)...

Ive shot identical,loads in AR brass in my 625, pretty much identical results. Modern AR brass has the same volume as acp brass.

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NRA Cert. Inst. IDPA CSO

It has been mentioned that the 45 AR case at one time was built with “balloon head” construction (by the way, when introduced the makers referred to it as a solid head compared to the old folded head cartridges. You can even find cartridge cases with a “S H” headstamp.). Since it was introduced AFTER the introduction of the 45 ACP, it begs the question “Was the 45 ACP ever produced with the balloon head construction?”

Kevin

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Unshared knowledge is wasted.

I believe 45AR has slightly less case capacity I was always under the understanding that 45AR had a thicker base and was built to handle 45super pressures.

Just curious but how would one identify one of the old "balloon head" cases?
I ask because I came into some hand loaded 45AR cases at a garage sale a while back and bought them with the intention of breaking them down and recharge them with new powder, re-using the brass, primer, and bullet.
So how can I confirm they aren't balloon head cases? How old would they have to be to be balloon head? Are there specific brands or markings to look for?

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Send lawyers, guns & money...

Me too......Always have.......Always will. Why sweat the little stuff?

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S&W Accumulator

Broken down the inside of the brass should be smooth to the primer. If it has an opening near the rim it is a balloon head.
Balloon head brass picture - Google Search
I hope the pics help.

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Front sight and squeeze

Thanks. Should be pretty easy to spot. I was wondering if there were easy to see external differences as well. Thanks again.

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Send lawyers, guns & money...

No balloon head brass here. Just shiny new Starline.

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What could possibly go wrong?

Wouldn't you know it: GRAFS actually has STARLINE .455 Webley brass in stock & available...!

Wouldn't it just figure?

Cheers!

The reason why reloading manual data for the 45 Auto Rim is less powerful than for the 45ACP is because SAAMI max spec for the 45AR is just 15K CUP while the 45ACP is 18K CUP. (The 45 Colt max is 14K CUP)

There is no SAAMI standardized max PSI pressure established for the 45AR, which is 21K PSI for the 45ACP

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Here's some data I measured/collected when I started loading for the 45 Super.

All were from new unfired Starline brass.

Starline says their 45AR brass has the same integrity as their 45 Colt brass, which is every bit as strong/stronger than their 44 Magnum brass.

I've loaded their 45AR brass with the same load as my full 45 Super loads, without issues.

I've loaded their 45 Colt brass to starting 454 Casull loads without issues.

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I load my M325/625s revolvers mainly with 45 Auto Rims.
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Waiting for the break of day

I use the same 200 gr rnfp bullet and powder charge for 45acp and 45ar but have found the load spicier feeling in my revolvers. Of course this is due to the autos recoil being soaked up by the slide movement. I tend to download my 45 revolver ammo to be gentler to my 70 year old hands. Don’t have a problem with a 1911.