45AutoRim: The Great Survivor

I guess I can understand reworking a gun to use that many cases.

Years ago when fountain pens were on the way out, I had an 8 oz jar of ink. I kept buying fountain pens just to use up the ink. I finally threw both the pens and the ink away and went to ball pens like the rest of the world.

BTW, the SAAMI pressure spec for the .45 AR is 15k psi, vs 21k for the .45 ACP, so the factory .45 AR is loaded a lot lighter than the .45 ACP.

Jim
Click to expand...

Jim,

Not really but I know what you are getting at. Meaning the SAAMI spec is 15k CUP which is different than PSI. In my research you find in cartridge loading books from the historians or experts that the reason the SAAMI pressure spec is lower is due to originally how Peters loaded the cartridge with a soft lead bullet.

Some of the reloading books adhere and some of them give caution. For example Speer specifically calls out the SAMMI spec for AutoRim is 15KCUP but state all of their 45AR loads are within 45Auto pressure of 21kPSI.

It is safe to use 45 Auto factory ammo / SAAMI spec in today's revolvers. I would not use +P or +P+, if I need that kind of power I just always go up to the next caliber anyway. Chose the right pistol and ammunition for the job.

Respectfully,
Mr.Revolverguy
 
The fact that I forgot to take my moon clips to the range with me a number of years ago was the only thing that kept me from killing my Brazilian copy of my 1917 Smith & Wesson.

I didn't feel like shucking .45 ACP cases out of it with a pencil, so I left it in my case and moved on to my 1911. The second or third round was a double charge of WW 231, almost 10 grains, the result of me loading on a new press and not paying adequate attention to what I was doing.

It was pretty spectacular when I pulled the trigger, but the 1911 wasn't hurt, and neither was I. The magazine was trashed, but I have absolutely no doubt that it would have opened up the cylinder on my 1917.
 
Last edited:
I find another benefit to reloading Auto-Rim...the cases fall into your hand.

Picking up spent cases is not as much fun as it used to be!

Bob
 
Hi, RevolverGuy,

Apologies to all because the .45 AR 15k pressure is indeed listed in CUP. Now just how does that differ from PSI and does that negate the statement that the AR is loaded to a lower pressure than the .45 ACP? Maybe you can offer a full explanation of the difference and a conversion formula, along with the actual pressure figures for factory ammo in the same system. It would also be nice to know exactly how much pressure the old Model 1917's and their modern counterparts can handle.

Jim
 
Much of what I've seen indicates that firing FMJ .45 ACP/AR ammo loaded to military standards really isn't such a great idea in World War I Model 1917 Colts or S&Ws.

The World War I guns were made in great haste to fulfill military contracts, and I've seen claims that standards of heat treating were relaxed to get the guns manufactured and into the military's hands as quickly as possible.

Additionally, S&W had so many issues in producing these guns that production was actually taken over by the US military during the war.

One article I saw some years ago claimed that chamber mouths were intentionally held large to reduce overall chamber pressure.

Most of the .45 AR reloading data I've seen over the years has also been reduced below standard .45 ACP pressure, presumably for the reasons I've listed above.

I don't shoot jacketed bullets in my M1917 Brazilian Contract, and I generally use fairly moderate loads.
 
Jim,

I hope I did not upset you in anyway, as it was not intended that way. There are many of men who work in the science of ballistics whom have taken a run at this and are way more qualified than I to answer your question. So I will lean on their experience to give a shot at answering your question.

Ken Oehler had some articles in shooting times magazine way back and he stated there was no direct correlation between CUP and PSI pressure. He is a guy I would tend to really believe on this point. Considering he has built pressure testing equipment for ammo manufacturers I would say he is qualified. In short according to Ken Oehler there is no way or formula to translate between CUP and PSI.

Many years later Speer came along with something different. They actually posted on their website that there seemed to be a close relationship in CUP and PSI as it pertained to rifle cartridges. But absolutely no relationship in pistol cartridges. That article over time has since been taken down and is hard to find.

As a definitive answer I would say follow the loads in your most up to date reloading manual. Most new reloading manuals will have 45AR loads reduced under 45ACP loads. But looking at 3 new manuals this morning some powders are only a tenth of a grain or so reduced.

To add a little confusion ;) I am looking at a reloading manual produced in 1980 and all of their 45AR loads are significantly higher than 45ACP for the same bullets.

This is where the true art of reloading comes into play. I would use a new manual for any 45AR loads no matter the pistol intended 1917 or modern day 625 and start at the very lowest point in the "new" manual and stop when I get a reliable accurate functioning load.

Mr. Irwin has also given some very sound advice and rules of thumb or guidelines to follow.
 
You must log in or register to reply here.
Back
Top