Are .45 auto rim and .45 ACP loads the same?

[alwslate]

Are you sure that you're not confusing the normal ring left near the
case head by the sizing die with swelling? Your loads are low
pressure. I'll bet that a few good pics of the cases you are concerned
about will quickly lead to the answer.

 

[dmy]

I don't think I am confused, but how would a confused person know that?

Alwslate:
I am aware of the ring around the base of various cases, including my .45 auto rim cases, caused by the sizing die not resizing 100% of the case length. I presume this lower portion of the case is not causing the problem or at least it is not related to the lack of 100% resizing because I always put the first few finished cartridges through the plunk test using the actual revolver. In essence, I put each auto rim cartridge through the plunk test when I load it at the range. They all fall into the chambers like a hot knife through butter. When ejecting the empty case, some of the loads (as in all 50 cartridges previously loaded with that same bullet, powder, and charge) are sticky to difficult to eject. All of my auto rim cases were purchased at the same time and bear the same original lot number. I have never had the same problem with .45 acp cases, even when using factory 230 FMJ loads which are, by far, the hottest load I have put through my 625. Again, thanks for your response which is good knowledge.

 

[alwslate]

Ok the only thing I can say is a few good pics illustrating your problem
would most likely quickly lead to some advice. The old saying "one
picture is worth a thousand words" still rings true.

 

[dmy]

Will do next time

Thanks Alslate. I will try my first attempt at posting photos the next time I have this problem. Currently, all of my auto rim cases are either loaded or already sized, deprimed and cleaned.

 

[Warren Sear]

THREAD DRIFT ALERT!!!

In my experience, if you check an Auto Rim[AR] case and an ACP case for water volume you will find the AR case has less case capacity. Either way, unless you are loading max. loads there will be little difference in performance.
The ACP or AR can both be loaded to equal, or better than a .45 Colt in modern guns.
If the subject really intrigues you ,try to find a copy of the article " The Best .45 Autos are Sixguns" by Skeeter Skelton, in the June 1973 issue of "Shooting Times" magazine.
For "hot rodding" the ACP you will be amazed at what can be done in the S&W 1955 Target and later versions, or if you're after ICBM ballistics try the Ruger .45 Blackhawk convertibles. You could nearly sell off your .44 Mags.! Best of luck in your pursuit. Nick

I have encountered that claim before, but do not understand how it can be true. Given similar pressure limits and bullet weights, the 45 Colt will always out-power the 45 ACP. That is like claiming the 308 Winchester will out-power the 30-06.

I don't think so.

I had no luck trying to find the Skeeter Skelton Article on line.

 

[Ed Fowler]

A long time ago I read a very serious debate concerning the differences between rimmed and rimless cartridges, pressure and tolerances. Those debating were of the vintage of Phil Sharp, Harvey Donaldson and Howe, I am not sure about the names of those in the discussion. Some favored the rimmed cartridge over the rimless and naturally there was the other side. The discussion got very technical and was very interesting to me. I have searched through my old books and cannot find the article.

I would appreciate it if anyone can come up with a reference.

One thing I have noticed is that my the rims of my Starline AR brass swell over time and after about 40 reloadings will not fit in my shell holder. Once I accidentally loaded way too much powder in one cartridge and recoil was strong, the bullet hit about 7 inches low at 50 yards, but the case did not stick and with a micrometer I could not find any differences between it and the other spent cartridges, nor could I see any difference in the primers that would indicate high pressure.

Any thoughts will be appreciated.

 

[Coastie762]

I use both Rem and Starline AR cases, loading both using .45 ACP data without any problems. These are used in two 625-8's (a JM and a PC) along with a 5-screw 1955 Target.

Most are loaded with my standard 230 grain load (LRN, FMJ or plated) over of 5.0 grains of Bullseye. Works well enough for my purposes.

 

[moosedog]

If your getting flattened primers and hard extraction (true signs of high pressure) is there a chance your AR brass is the old "balloon head) cases that actually have less interior space?
I know they have not been made for years but just checking a possible.

 

[Warren Sear]

If your getting flattened primers and hard extraction (true signs of high pressure) is there a chance your AR brass is the old "balloon head) cases that actually have less interior space?
I know they have not been made for years but just checking a possible.

Actually, the balloon-head cases have MORE space, not less than solid-head cases.

It probably takes about 40,000 psi to flatten standard large pistol primers, and perhaps 50,000 to make cases start to stick to chambers (assuming cases and chambers walls are within specs). So, those pressure signs (which pertain to rifle pressures, not typical handgun pressures) have no application to the 45 AR, 45 ACP or 45 Colt.

See the second half of post #26 above.

 

[BruceM]

In fact many of the more recently produced 325/625 chambers either don't have the "shelf" that permits headspacing on the case mouth for ACPs without moon clips or the shelves are cut too deep to be of any use. S&W chooses to ignore this, knowing that the ACP cartridges will headspace just fine on the moon clips.

This may be true in guns of recent manufacture but it was not the original intent of the design of the 1917's, M25-2's or the 1950 and 1955 Target .45's. I can't tell you how many old timers I've seen at the range knocking spent .45 ACP cases out of these guns with a short dowel or pencil because the half moon clip then provided with these guns were such a pain in the gazanski to deal with. In the case of the 1917's, the guns needed to operate under combat conditions even if the half moon clips were lost in action. In essence, Smith and Wesson did not go to the expense and trouble to machine the shelves in the chamber of these guns just for grins.

So, it's my understanding that the original design intent of the .45 Auto Rim case was to provide a mechanism to facilitate spent case extraction without the use of half moon clips and not to provide a headspacing index point.

Bruce

 

[moxie]

No, the rim on the AR does both. It provides a headspacing datum and allows for extraction. That quote is mine. Yes the older 1917s, 625s, etc., like my 625-3,have properly cut chambers that permit headspacing on the case mouth without a moonclip. But when you use ARs in those guns the rounds don't seat quite as deep, so they do in fact headspace on the rim, not the mouth.

BTW,I am one of those oldtimers you see at the range, but I usually don't need a pencil or dowel when I choose to not use a clip or ARs. Just a little shake and they fall right out.

 

[Bearbait in NM]

Just as a data point, my newer 625 PC will headspace taper crimped 45acp just fine. It also works with the clips, the 45AR taper crimped, and 45AR that is roll crimped.

Craig

 

[flintsghost]

Be very careful about assuming loads are the same in 45 AR. It depends entirely on the brass. Before using ACP loads in AR check every AR case to make sure you don't have any of the old "balloon head" cases in AR. If you do you should weed them out. They will not stand the pressure of modern ACP loads that are close or on the max line.

If you don't know what "balloon head" cases are you will need to do some research so you can recognize them. When you look down in them they are deeper and have a larger case capacity and the rim is fairly weak.l They have not been made in a lot of years. But they were common in AR case construction at one time just as they were also used in 45LC. I still see them once in a while, usually in fired brass, at gun shows.