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.45 Auto Rim vs. .45 ACP

19K views 13 replies 8 participants last post by  MAC702  
#1 ·
I've been crusing this and other forums trying to get a handle on relaoding the .45AR.
I have a VERY clean S&W 1917 in VERY good condition. Since this gun was designed to augment the short supply of 1911's it was designed to fire the standard .45 hardball 230gr.
So much for history: I keep reading that the .45AR cannot be loaded to ACP pressures and that the original 1917 isn't safe with ACP loads. I understand what I read, I don't understand the logic given the original purpose/history of the gun. Can I fire standard .45ACP rounds in the gun or not? Starline brass says they make the AR brass to the same standards as the ACP. This gun is SOOO sweet with an action that is butter smooth. I'm rambling....

So what's the drill? I'd like to bring the AR reloads up to, but not in excess of the ACP. Thanks to all in advance....
 
#3 · (Edited)
I've seen some reloading data also, that list max loads for the auto rim as slightly less than the 45 ACP. I'm not really sure why. The 1917 revolver was made to shoot the same 45 ACP ammo which was interchangable with the 1911 pistol. About 17,000 psi for hardball. The auto rim case is the same as the ACP, except for the rim. That's what the manufacture's intent was.
In my model 25-2 S&W, I first hated using the full moon clips and purchased several hundred auto rim cases, Remington and Starline. None of my progressive presses would load them, so I had to single stage them. The rim is an oddball size. That got old fast, so I later returned to the full moon clips with ACP brass and never looked back. I snap the rounds in the clips as I reload them and I store them that way. It's a lot neater and faster at the range, and I demoon them when I get home.
 
#11 ·
I have my Dillon 550 set up to load both .45 ACP and .45 AR by changing only the shell plate. I taper crimp both and load them identically. I also tend to load them both a little light for no particular reason.

Little current .45 AR data seems to be available. I use .45 ACP data and start low. Hogdgon has their on-line site with .45 ACP.

http://data.hodgdon.com/cartridge_load.asp
 
#4 ·
I would double-check the sameness of the brass. SAAMI only specifies external dimensions, so the manufacturers can play with the inside to their heart's content. Considering the variance between brands of brass, it could be as simple as the loads developed for the auto-rim having been done with a brand of case or a case lot that had less capacity than regular ACP cases? And it might not be true for whatever brand you buy today? To tell, just find the water capacity of the case by weighing them filled with water and again empty and taking the difference. See if they both hold the same number of grains of water, on average? A smaller case capacity will cause higher pressure in a given load.

The only reason I can think of for warning not to use .45 ACP in the 1917 would be to avoid +P loads or other modern loads with higher peak pressure than original hardball?
 
#5 ·
If I were a brass/ammo manufacturer, I think I'd put some caution warnings on 45 AR ammo, too. Why?
45 AR ammo is a pretty sure bet to be used in a handgun that's nearly 100 years old, and produced under the pressure of wartime production deadlines.
45 ACP brass/ammo is far more likely to be used in a newer handgun, and a platform known for it's ruggedness.
Other than that, the only thing I can think of that would make a difference between the ACP and AR brass is the internal capacity, as UncleNick suggests.
 
#6 ·
.45 Auto Rim

Jack, I would appreciate the reloading info from Speer, when you can.

GBertolet, I have a demooning tool that makes it all easier on the fingers, although still time consunming. I can't remember where I got it.......

Unclenick, I'm only interested in standard loads, I save the +P's for the autos
 
#9 · (Edited)
It's strange that the one bullet Speer doesn't have data for is the 230 grain TMJ (jacketed round nose). For the lead round nose, max is 6.6 grains of Unique and 4.5 grains of Bullseye. The loads they list for the 225 grain jacketed hollow point are well over any current data and must go back to Speer's HOT old days. .45 ACP data is even hotter. Max for Unique is 6.9 grains and max for Bullseye is 5.5 grains. I'd suggest you avoid these barnburners and use Alliant's current .45 ACP data.

http://www.alliantpowder.com/reloaders/recipedetail.aspx?gtypeid=1&weight=230&shellid=35&bulletid=69

Bye
Jack
 
#12 ·
.45ACP Reloads

Jack, thanks for yor input. Thought you might be interested in something that confused me:

Speer Reloading Manual (1994 Ed.)
230gr TMJ 5.7 Bullseye = 840fps
230gr. GDHP 5.0 Bullseye = 815fps

Is this odd or is it me?

I just picked up a new Lyman manual and I would have thought the same powder, same bullet and weight, same 5" barrel then why is the powder load and vel. different? I have an old Hornady, this Speer and the new Lyman but, the inconsistencies do not give me confidence, since I see this in .45 and .38/.357 as well. I can understand lead vs. jacket and differences in barrell length, but in careful reading it seems as though some scales are WAY off. As Glenn Beck says "...it makes blood squirt out of my eyes" I guess I'll just start using averages..............