SAAMI pressure 45 Colt vs 45 ACP

[rusty gunns]

As I had mentioned in a post yesterday, I have decided to sell my modern rifles and pistols and purchase originals.

I was taking some pictures of a 10 year old Mitchel/Uberti pistol I've decided to sell. It's got a 4 1/2 bbl and twin cylinders. One is 45 Colt, the other 45 ACP.

Here is the question I have often asked myself.

Now, the SAMMI pressures for 45 Colt are 14,000 and the 45 ACP is 21,000 (though most ACP reloads don't seem to exceed 17 or 18k. Hodgdon HP-38, for example. 7.3 gr yields 13,700 in 45 colt, and 5.3 gr yields 16,900 in the 45 ACP. Both for a 230gr lead bullet). The cylinder walls are the same thickness and the bullets close enough in size (diameter) and weight to be a non issue. And I'm sure the steel is the same in both cylinders. I know the dynamics of both rounds are very different. And that the same amount of the same powder in each yields different pressures.

In order to handle the higher pressures, A 38/357 has to be, in reality a 357. It simply can chamber and fire the lesser 38 cal bullet.

I would NEVER load a 45 colt anywhere near 45 ACP pressures, nor do I endorse the practice, but I often wondered that, given the higher pressures the gun can take firing the 45 ACP round, could it handle 45 Colt rounds nearing that pressure?

Is the question as stupid as the act?

Disclaimer:
Boys and girls, NEVER try this at home unless you are a trained mental deficient.

[Chas.]

What seems to get lost sometimes is that pressure is expressed in pounds PER SQUARE INCH (or CUP). So if you have a cartridge at 16,900 psi and the shell case is a total of, say, 2 square inches, then the total force against the chamber is 33,800 pounds. Now if a larger case is used and it's, say 3 square inches, then the total force is 50,700 pounds.

Have I successfully contributed to the confusion?

[Hobie]

Many of us DO load the .45 Colt to .45 ACP pressures, albeit with the 255 gr. Keith or 270 gr. Scovill bullet.

[J Miller]

As I had mentioned in a post yesterday, I have decided to sell my modern rifles and pistols and purchase originals.

I was taking some pictures of a 10 year old Mitchel/Uberti pistol I've decided to sell. It's got a 4 1/2 bbl and twin cylinders. One is 45 Colt, the other 45 ACP.

Here is the question I have often asked myself.

Now, the SAMMI pressures for 45 Colt are 14,000 and the 45 ACP is 21,000 (though most ACP reloads don't seem to exceed 17 or 18k. Hodgdon HP-38, for example. 7.3 gr yields 13,700 in 45 colt, and 5.3 gr yields 16,900 in the 45 ACP. Both for a 230gr lead bullet). The cylinder walls are the same thickness and the bullets close enough in size (diameter) and weight to be a non issue. And I'm sure the steel is the same in both cylinders. I know the dynamics of both rounds are very different. And that the same amount of the same powder in each yields different pressures.

In order to handle the higher pressures, A 38/357 has to be, in reality a 357. It simply can chamber and fire the lesser 38 cal bullet.

I would NEVER load a 45 colt anywhere near 45 ACP pressures, nor do I endorse the practice, but I often wondered that, given the higher pressures the gun can take firing the 45 ACP round, could it handle 45 Colt rounds nearing that pressure?
Yes, the gun can take the pressure. It's not overly complicated. Pressure is pressure. If the ACP cylinder can take the 21000K PSI, the .45 Colt cylinder will too.

Is the question as stupid as the act?
The question is not stupid and neither is the act. Many of us have shot heavier loads in our Colts, and Colt copies with absolutely no problems at all.

Disclaimer:
Boys and girls, NEVER try this at home unless you are a trained mental deficient.
Thank you Dr. "rusty gunns" for the professional psychological analysis. Or should I say insult. I'm sure there are
many of us on the forum who appreciate it as much as I do.

I do not know much about math other than 2+2=4. But what I do know is that every .45 Colt revolver ever made, has either been made with an auxiliary .45 ACP cylinder or come in a .45ACP model.
Pressure is pressure, and in this instance I cannot see how the difference in case length can cause the shorter cartridge at 21000PSI to be OK, but the longer cartridge at 21000PSI is not.
That argument makes no sense.

Joe

[adirondakjack]

Yes, pressure is pressure, and you can and we do. The reason it is ok is even though ya have more gas volume with .45 Colt, the pressures only matter in those places where they are concentrated, IE the place where the fire gets lit. Both cylinders can take it. The frames and such only care how heavy a bullet launched how hard, regardless of chamber size.....

[rusty gunns]

I have learned a lesson today, my friends.

If my attempt at a humorous ending to my post has offended anyone... my apologies.

I shall endeavor to make my inquiries more in the line of a simple question.

And thanks for the education. I guess my assumption that the gun could handle the load was reasonable after all.

[J Miller]

I have learned a lesson today, my friends.

If my attempt at a humorous ending to my post has offended anyone... my apologies.

I shall endeavor to make my inquiries more in the line of a simple question.

And thanks for the education. I guess my assumption that the gun could handle the load was reasonable after all.

rusty,

I suppose I should apologize too. I've been a bit touchy lately. One of the problems with forums or any text communication is that humor and sarcasm is very hard to to get when you can't see the person posting it, and all you have to go by is the text.

Your question is valid and a lot of people come to the conclusion that the bigger case of the .45 Colt somehow makes the higher pressure something worse than it is.

What I do is go back in history and use this as a basis for my thoughts on the .45 Colt pressure. Elmer Keith started experimenting with his bullet with the .45 Colt back in the 1920s. The Colts he used were obviously 1ST generation Colts. He wanted a heavier flat nosed bullet and a bit more velocity for hunting and defense. He tried various things but in the end he landed on the load of 18.5grs of Hercules 2400 under his 260gr SWC put up in balloon head cases. He never blew one up with that load. And according to (I never can remember which) either John Taffin or John Linebaugh, 18.5grs of 2400 under a 260gr Keith in modern cases runs around 25,000 psi. I would guesstimate that with the larger powder capacity of the balloon head cases his load was running around 21,000 to 22,000 PSI.
So using this as a basis there is no way a 21,000 psi load is going to harm any smokeless Colt SAA or Colt Copy that is in good mechanical condition.

OBTW, Do you remember my posts about IJ? Steve Young rebuilt it for me and even with the battered frame he told me it would take Keith's load without a problem. That's good to know, but I've not tried it yet. Perhaps someday.

Joe

[CJM]

SAAMI specs are for the cartridge - the gun that fires the cartridge may be able to withstand a much higher pressure level. An old Colt SAA from the 1870's probably won't be able to withstand a pressure level of 21,000 CUP, even if a modern version made with much better modern steels can. Yet both are chambered for 45 Colt cartridges and should be able to fire any factory made 45 Colt cartridge. So the SAAMI limit is low to allow the old guns to survive, even if new guns won't have problems.

[adirondakjack]

SAAMI specs are for the cartridge - the gun that fires the cartridge may be able to withstand a much higher pressure level. An old Colt SAA from the 1870's probably won't be able to withstand a pressure level of 21,000 CUP, even if a modern version made with much better modern steels can. Yet both are chambered for 45 Colt cartridges and should be able to fire any factory made 45 Colt cartridge. So the SAAMI limit is low to allow the old guns to survive, even if new guns won't have problems.

And the sky is blue. I think we all knew that. The issue at hand is what to do when confronted with a .45 Colt type revolver with one of the older type (clone) actions that we are told not to hotrod to Ruger-only levels, but we know in fact are also offered with .45 ACP cylinders. It doesn't take a rocket scientist to see the guns will handle ACP pressures, and need not strictly be limited to SAAMI load levels suitable for very early smokeless guns. Still gotta go a bit easy, for they are not up to the hottest stuff, but reasonably warm (ACP-pressure) loads are ok.

[adirondakjack]

To All:

I happened to meet Rusty Gunns at a CAS event last weekend. As is often the case, I remembered this thread, but not who said what (I am far more interested in ideas that who spoke them). ANYWAY he certainly remembered the thread, and my take on it is he was making an attempt at levity in his OP. Seems like an OK guy to me.

[J Miller]

A-jack,

I came to that realization after the fact. That's why I made my apology.

I think I need an ACP cylinder for IJ. That would be fun.

Joe

[Hobie]

Well, sorry about that.

[awp101]

I was taking some pictures of a 10 year old Mitchel/Uberti pistol I've decided to sell. It's got a 4 1/2 bbl and twin cylinders. One is 45 Colt, the other 45 ACP.

Ohhh, you have my attention...price?

[rusty gunns]

I was taking some pictures of a 10 year old Mitchel/Uberti pistol I've decided to sell. It's got a 4 1/2 bbl and twin cylinders. One is 45 Colt, the other 45 ACP.

Ohhh, you have my attention...price?

Advanced Levergunner

re that pistol.
Email me at webmaster1@roadrunner.com.

I think you'll like the price.