.45 auto rim case expansion

DMY · January 4, 2016, 12:23 AM

I shoot both .45 acp and auto rim cases out of my S&W 625. Lately, my auto rim cases have been expanding excessively after firing which makes the empties very hard to eject. I am afraid I might bend the ejected rod. I do not have the same problem with acp brass and the cylinders on my revolver were previously polished. I know my brass is properly sized because they pass the plunk test and load easily. I use Remington auto rim brass and load relatively light loads (4 to 4.5 grains of Bullseye over 200 to 230 grain lead or coated bullets or similar). I have probably reloaded these cases about 10 times. I know cases typically expand during shooting, but the exact same load causes problems with auto rim, but not acp. Has anyone else had similar experiences, and if so, how did you resolve it?

stubbicatt · January 4, 2016, 06:17 AM

Wow. I'm glad I stumbled across this thread this morning, as I was about to load some auto rimmed cases this morning which I bought sometime last year. I haven't opened the box yet, so I can't say what brand they are.

The auto rim cartridges have used these same loads about 10 times without this sticking in the chambers? Have you trimmed them recently? It seems unlikely that they would get long enough to cause you a pressure excursion, just due to the design of the chambers in the 45 ACP revolvers I know of. You know, the headspacing on the case mouth... if they were too long you probably couldn't close the cylinder. If you use a roll crimp maybe? But it might be worth measuring their length.

I am not familiar with your loads, as I haven't used Bullseye in many years. My immediate reaction is to double check everything. The chambers/charging holes cleaned properly? Ejector rod works properly? Then I guess double check some of your cartridges, pulling the bullets and weighing the charges. Maybe your powder measure got misadjusted or something? I suggest this as it sounds to me like too much pressure, which I can't account for otherwise.

Do you suppose maybe the brass is just worn out? One of the features of 45 ACP in my experience is that the brass lasts a very long time due to its lower operating pressures. Like I said, I haven't tried auto rim yet.

Good luck. I'll be subscribing to this thread as this has my attention.

JT-AR-MG42 · January 4, 2016, 06:30 AM

Maybe post back with case dimensions.

Your loaded round neck and base.
The fired round neck and base.

I've not experienced fired and x times reloaded brass
(relatively low pressure straight pistol cases) to give me any
troubles like you describe, especially with the target velocity load you are using.

And I do reload .45AR. - S&W 25-2

JT

243winxb · January 4, 2016, 10:00 AM

Quote:

expanding excessively after firing which makes the empties very hard to eject.

High pressure, reduce the powder charge. Be careful using coated bullets. Nickel plated brass will not spring back like plain brass after many firings. If your using nickel?

DMY · January 4, 2016, 05:03 PM

Thanks for your responses, suggestions and follow up questions. I don't have my cases or calipers with me at the moment and will follow up with some additional data. My calipers are not digital, so I will do my best to "read between the lines" on the exact dimensions of the case neck, base and length of fired and unfired rounds. I might have trimmed these cases many years ago when I first bought them, but I haven't trimmed or measured them since. I do chamfer and deburr the cases after reloading them about 5 times or so.

To elaborate, the Remington AR brass have been reloaded approximately 10 times. I have reloaded the various ACP brass many more times without any problem. I use a roll crimp on my AR brass (standard on a RCBS 3-die set) with just enough crimp to pass the plunk test. The new rounds load and plunk fine without any apparent head space problem because the cylinder closes with ease. I do not recall having this problem during the first several times I reloaded this same brass.

My 625 is rather tight between the cylinder and firing pin side of the receiver which is exemplified by requiring my moon clips (used with ACP) to be stoned before the cylinder will close with ease. I have never had trouble closing the cylinder with AR rounds.

As to my reloads, I have never come close to reloading maximum loads. Typically, my loads are between the minimum load to just about mid-range. In addition to the Bullseye loads I referenced, my most recent problem was experienced with AR brass, Hornady 200 gr LSWC over 4.9 - 5.0 grains of TightGroup with a CCI primer. I know my loads are very light compared to
factory 230 gr FMJ in ACP which I have shot. Again, I have never had any problem ejecting ACP brass either from factory loads or my reloads. All of my AR and ACP cases are brass. I have never reloaded nickel cases in .45. Many years ago when I reloaded high velocity .357 loads, I did have a few cases which expanded (bulged) due to high pressures and they were also hard to eject. During those years, I did reload towards the maximum levels, but again, that was a different gun and different caliber. My recollection is that heavy loads cause cases to bulge and light loads cause cases to lengthen. I did not notice any signs which indicated that the cases might have lengthened after firing such as rubbing against the back of the receiver.

During my last session where I experienced this problem, I used the exact same load in ACP and AR brass (200 gr LSWC over 5.0 grs of TightGroup). The only difference was the AR round had a slight roll crimp and the ACP brass had a slight taper crimp. The recoil differential between these two rounds was insignificant, so I presume the pressure differential was also relatively small. It is possible my gun was a little dirty since I had not cleaned it after the last 500 rounds or so. But again, the unfired bullets dropped in without any resistance.

One additional thing I noticed was that the spent ACP brass from my 1911 has a little soot mark on one side of the case whereas my 625 does not leave the same soot mark. I presume the chamber of my revolver is a little tighter, but again, the live rounds easily pass the plunk test.

One thing which came to mind was that it may be possible that the rim of the AR case is forming a tighter seal against the chamber and cylinder which prevents some gases from escaping out the back. The lack of an easy exhaust path may be causing the brass to expand excessively. This seems a little far fetched since the path of least resistance for the gas is to go forward through the barrel / cylinder gap rather than in reverse towards the case rim.

Another thought was that the Remington AR brass might have thinner walls than any of my ACP brass. I do not have the ability to measure the case thickness, but I use a variety of ACP brass (S&W, Federal, IMI, W-W, WWC, R-P and PMC) and have not had problems with any of them in my revolver. I only have one brand of AR brass.

I will follow up with some dimensions, probably later tonight. Thanks again for your comments and input.

DMY · January 4, 2016, 10:15 PM

I measured 3 fired auto rim cases, 3 resized and empty auto rim cases, 3 fired acp cases, 3 resized and empty acp cases and 3 loaded acp rounds. I do not have any loaded auto rim cases (to my surprise). The measurements were fairly consistent and did not reveal any obvious reason for the cases to stick.

AUTO RIM CASES - fired:
Length: 0.885"
Case mouth: 0.46" - 0.47" dia.
Case middle: 0.47" - 0.474" dia. (2 were 0.47" & 1 was 0.474" dia. and all of them appear to stick upon ejection.)
Case above rim: 0.465" dia.

AUTO RIM CASES - empty and resized:
Length: 0.89"
Case mouth: 0.46" dia.
Case middle: 0.46" dia.
Case above rim: 0.465" dia.

ACP CASES - fired:
Length: 0.885" - 0.889"
Case mouth: 0.46" dia.
Case middle: 0.47" dia. (none of these stuck upon ejection).
Case above rim: 0.465" - 0.467"

ACP CASES - empty and resized:
Length: 0.885" - 0.889"
Case mouth: 0.461" dia.
Case middle: 0.46" - 0.461" dia.
Case above rim: 0.465" dia.

ACP ROUND - loaded with taper crimp:
Length: 0.879" - 0.880"
Case mouth: 0.469" dia.
Case middle: 0.461" dia.
Case above rim: 0.461" - 0.465" dia.

One other thing to add to my prior observations. The cases primarily stick when I start ejecting them. After approximately 1/2 of the case lengths are out of the chambers, then they eject easily.

Any thoughts?

243winxb · January 4, 2016, 10:36 PM

Fat middle on the AR. The head and mouth are smaller. That's why they stick part way out. Reduce powder charge for that brass.

stubbicatt · January 5, 2016, 07:22 AM

I'm sorry I don't know what as fired length should be on the rimmed cases. But I wonder, since you roll crimp them, even if they were just a skosh long, they would likely still chamber as there might not be any contact between the case mouth and the headspace ring the front of the chambers. If they were too long, and if the crimp unfolds when they are fired, perhaps the case mouth is being forced or ironed over the end of the chamber, you know that point where a non rimmed cartridge would headspace on the case mouth? If it were doing that, then perhaps the initial extraction force would increase? Pressure surely would increase if there were a constriction at the case mouth, even if it were the same powder charge.

Just an idea, but if the same load has been just fine all this time, no undue ejection force, then something has changed. Either the powder measure got out of adjustment and you inadvertently overcharged the cartridges, or maybe length slowly crept up to the point where it is now the issue?

I don't know the answer but those two variables seem to be the only likely culprits. Too much powder or too long cases? Maybe a .454" bullet?

DMY · January 5, 2016, 09:40 PM

Thanks Stubbicatt. I tend to agree with your logic on possible case lengthening. The reason I don't believe it was a true over charge is because I use a single stage press, separate powder measure and look at the charged cases before seating the bullets. In addition, the recoil was very mild and the expansion in the middle of the case was the same as my acp rounds, which do not stick. I plan to check the case lengths before my next reload and also compare it to my Lyman manual for the proper length. As always, I greatly appreciate knowledgeable responses.

January 4, 2016, 12:23 AM	#1
DMY Senior Member Join Date: September 10, 2015 Posts: 152	.45 auto rim case expansion I shoot both .45 acp and auto rim cases out of my S&W 625. Lately, my auto rim cases have been expanding excessively after firing which makes the empties very hard to eject. I am afraid I might bend the ejected rod. I do not have the same problem with acp brass and the cylinders on my revolver were previously polished. I know my brass is properly sized because they pass the plunk test and load easily. I use Remington auto rim brass and load relatively light loads (4 to 4.5 grains of Bullseye over 200 to 230 grain lead or coated bullets or similar). I have probably reloaded these cases about 10 times. I know cases typically expand during shooting, but the exact same load causes problems with auto rim, but not acp. Has anyone else had similar experiences, and if so, how did you resolve it?

January 4, 2016, 05:03 PM	#5
DMY Senior Member Join Date: September 10, 2015 Posts: 152	Further information to follow Thanks for your responses, suggestions and follow up questions. I don't have my cases or calipers with me at the moment and will follow up with some additional data. My calipers are not digital, so I will do my best to "read between the lines" on the exact dimensions of the case neck, base and length of fired and unfired rounds. I might have trimmed these cases many years ago when I first bought them, but I haven't trimmed or measured them since. I do chamfer and deburr the cases after reloading them about 5 times or so. To elaborate, the Remington AR brass have been reloaded approximately 10 times. I have reloaded the various ACP brass many more times without any problem. I use a roll crimp on my AR brass (standard on a RCBS 3-die set) with just enough crimp to pass the plunk test. The new rounds load and plunk fine without any apparent head space problem because the cylinder closes with ease. I do not recall having this problem during the first several times I reloaded this same brass. My 625 is rather tight between the cylinder and firing pin side of the receiver which is exemplified by requiring my moon clips (used with ACP) to be stoned before the cylinder will close with ease. I have never had trouble closing the cylinder with AR rounds. As to my reloads, I have never come close to reloading maximum loads. Typically, my loads are between the minimum load to just about mid-range. In addition to the Bullseye loads I referenced, my most recent problem was experienced with AR brass, Hornady 200 gr LSWC over 4.9 - 5.0 grains of TightGroup with a CCI primer. I know my loads are very light compared to factory 230 gr FMJ in ACP which I have shot. Again, I have never had any problem ejecting ACP brass either from factory loads or my reloads. All of my AR and ACP cases are brass. I have never reloaded nickel cases in .45. Many years ago when I reloaded high velocity .357 loads, I did have a few cases which expanded (bulged) due to high pressures and they were also hard to eject. During those years, I did reload towards the maximum levels, but again, that was a different gun and different caliber. My recollection is that heavy loads cause cases to bulge and light loads cause cases to lengthen. I did not notice any signs which indicated that the cases might have lengthened after firing such as rubbing against the back of the receiver. During my last session where I experienced this problem, I used the exact same load in ACP and AR brass (200 gr LSWC over 5.0 grs of TightGroup). The only difference was the AR round had a slight roll crimp and the ACP brass had a slight taper crimp. The recoil differential between these two rounds was insignificant, so I presume the pressure differential was also relatively small. It is possible my gun was a little dirty since I had not cleaned it after the last 500 rounds or so. But again, the unfired bullets dropped in without any resistance. One additional thing I noticed was that the spent ACP brass from my 1911 has a little soot mark on one side of the case whereas my 625 does not leave the same soot mark. I presume the chamber of my revolver is a little tighter, but again, the live rounds easily pass the plunk test. One thing which came to mind was that it may be possible that the rim of the AR case is forming a tighter seal against the chamber and cylinder which prevents some gases from escaping out the back. The lack of an easy exhaust path may be causing the brass to expand excessively. This seems a little far fetched since the path of least resistance for the gas is to go forward through the barrel / cylinder gap rather than in reverse towards the case rim. Another thought was that the Remington AR brass might have thinner walls than any of my ACP brass. I do not have the ability to measure the case thickness, but I use a variety of ACP brass (S&W, Federal, IMI, W-W, WWC, R-P and PMC) and have not had problems with any of them in my revolver. I only have one brand of AR brass. I will follow up with some dimensions, probably later tonight. Thanks again for your comments and input.

January 4, 2016, 10:15 PM	#6
DMY Senior Member Join Date: September 10, 2015 Posts: 152	measurements did not reveal much to me. I measured 3 fired auto rim cases, 3 resized and empty auto rim cases, 3 fired acp cases, 3 resized and empty acp cases and 3 loaded acp rounds. I do not have any loaded auto rim cases (to my surprise). The measurements were fairly consistent and did not reveal any obvious reason for the cases to stick. AUTO RIM CASES - fired: Length: 0.885" Case mouth: 0.46" - 0.47" dia. Case middle: 0.47" - 0.474" dia. (2 were 0.47" & 1 was 0.474" dia. and all of them appear to stick upon ejection.) Case above rim: 0.465" dia. AUTO RIM CASES - empty and resized: Length: 0.89" Case mouth: 0.46" dia. Case middle: 0.46" dia. Case above rim: 0.465" dia. ACP CASES - fired: Length: 0.885" - 0.889" Case mouth: 0.46" dia. Case middle: 0.47" dia. (none of these stuck upon ejection). Case above rim: 0.465" - 0.467" ACP CASES - empty and resized: Length: 0.885" - 0.889" Case mouth: 0.461" dia. Case middle: 0.46" - 0.461" dia. Case above rim: 0.465" dia. ACP ROUND - loaded with taper crimp: Length: 0.879" - 0.880" Case mouth: 0.469" dia. Case middle: 0.461" dia. Case above rim: 0.461" - 0.465" dia. One other thing to add to my prior observations. The cases primarily stick when I start ejecting them. After approximately 1/2 of the case lengths are out of the chambers, then they eject easily. Any thoughts?

January 5, 2016, 07:22 AM	#8
stubbicatt Senior Member Join Date: September 15, 2007 Posts: 1,707	I'm sorry I don't know what as fired length should be on the rimmed cases. But I wonder, since you roll crimp them, even if they were just a skosh long, they would likely still chamber as there might not be any contact between the case mouth and the headspace ring the front of the chambers. If they were too long, and if the crimp unfolds when they are fired, perhaps the case mouth is being forced or ironed over the end of the chamber, you know that point where a non rimmed cartridge would headspace on the case mouth? If it were doing that, then perhaps the initial extraction force would increase? Pressure surely would increase if there were a constriction at the case mouth, even if it were the same powder charge. Just an idea, but if the same load has been just fine all this time, no undue ejection force, then something has changed. Either the powder measure got out of adjustment and you inadvertently overcharged the cartridges, or maybe length slowly crept up to the point where it is now the issue? I don't know the answer but those two variables seem to be the only likely culprits. Too much powder or too long cases? Maybe a .454" bullet? Last edited by stubbicatt; January 5, 2016 at 07:32 AM.

January 5, 2016, 09:40 PM	#9
DMY Senior Member Join Date: September 10, 2015 Posts: 152	thanks Thanks Stubbicatt. I tend to agree with your logic on possible case lengthening. The reason I don't believe it was a true over charge is because I use a single stage press, separate powder measure and look at the charged cases before seating the bullets. In addition, the recoil was very mild and the expansion in the middle of the case was the same as my acp rounds, which do not stick. I plan to check the case lengths before my next reload and also compare it to my Lyman manual for the proper length. As always, I greatly appreciate knowledgeable responses.

January 4, 2016, 06:17 AM	#2
stubbicatt Senior Member Join Date: September 15, 2007 Posts: 1,707	Wow. I'm glad I stumbled across this thread this morning, as I was about to load some auto rimmed cases this morning which I bought sometime last year. I haven't opened the box yet, so I can't say what brand they are. The auto rim cartridges have used these same loads about 10 times without this sticking in the chambers? Have you trimmed them recently? It seems unlikely that they would get long enough to cause you a pressure excursion, just due to the design of the chambers in the 45 ACP revolvers I know of. You know, the headspacing on the case mouth... if they were too long you probably couldn't close the cylinder. If you use a roll crimp maybe? But it might be worth measuring their length. I am not familiar with your loads, as I haven't used Bullseye in many years. My immediate reaction is to double check everything. The chambers/charging holes cleaned properly? Ejector rod works properly? Then I guess double check some of your cartridges, pulling the bullets and weighing the charges. Maybe your powder measure got misadjusted or something? I suggest this as it sounds to me like too much pressure, which I can't account for otherwise. Do you suppose maybe the brass is just worn out? One of the features of 45 ACP in my experience is that the brass lasts a very long time due to its lower operating pressures. Like I said, I haven't tried auto rim yet. Good luck. I'll be subscribing to this thread as this has my attention.

January 4, 2016, 06:30 AM	#3
JT-AR-MG42 Senior Member Join Date: December 27, 2008 Posts: 555	Maybe post back with case dimensions. Your loaded round neck and base. The fired round neck and base. I've not experienced fired and x times reloaded brass (relatively low pressure straight pistol cases) to give me any troubles like you describe, especially with the target velocity load you are using. And I do reload .45AR. - S&W 25-2 JT

January 4, 2016, 10:36 PM	#7
243winxb Senior Member Join Date: July 26, 2011 Location: USA Posts: 1,730	Fat middle on the AR. The head and mouth are smaller. That's why they stick part way out. Reduce powder charge for that brass.