Why are Revolver Casings so Long?

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Brownstone322

New member
Dumb question, probably, but humor me. Why are revolver casings so long compared to auto casings?

I own and shoot semi-autos, so I really have only marginal experience with revolvers (other people's). So why is a .38 Special casing 29 millimeters when a 9mm Luger generally gets better performance from a 19-millimeter casing with essentially the same bullet weight?

And it's not just the .38, it's lots of cartridges -- .32 Long, .357 Magnum, .44 Special, .44 Magnum, .45 Long Colt. Anything that's popular. My one guess: They're all descendants of black-powder cartridges that needed more casing capacity than we need now. (But I am making that up.)

Discuss.
 
Most revolver rounds were developed when black powder was the propellant . It takes a much larger volume of black powder to push a bullet to usable velocities.
To make more powerful rounds the case would be made longer and then longer.
Black powder 38 Short Colt was extended to get the 38 Long Colt which was extended to get the 38 special....this is when smokeless powder started replacing black powder but no going back now...the 38 Special was extended to make the 357 Magnum.

No semi-automatic rounds were ever , to my knowledge, developed and loaded with black powder...smokeless powder allowed the use of the short rimless cases .

Although you may be making your answer up...it's correct !
Smokeless powder allowed short cases and black powder required the long case.
Gary
 
In addition to the above, the primary reason that semi-auto brass is short is that people's hands are only so big so it limits how big the grip can be. As the mag slides up the grip in all but a few (Broomhandle Mauser C96 comes to mind as one that doesn't) the length of the rd is restricted to what will fit into a grip people can use.

More modern, higher pressure powders came along that allowed for 9mm, 40s&w, 10mm, 40 Super, 45 Super, etc. high pressure cartridges to be developed without the need for larger, magnum sized brass which allows for their use in a semi-auto.
 
My one guess: They're all descendants of black-powder cartridges that needed more casing capacity than we need now. (But I am making that up.)
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Your guess is pretty much spot on. All the regular revolver rounds were either originally black powder rounds, or were developed from cases that were.

Semi auto pistol rounds are short, for two reasons. First, they were all developed in the smokeless powder era, so case volume could be less than equal power black powder rounds, and second, the need to be short enough to fit inside the magazine in the pistol grip, comfortably.

.45 Colt - 1873 - black powder

.45ACP - 1911 - smokeless
for one example...

Modern design revolver cartridges are still "long" not because its needed, but because they are made to fit revolvers that aren't "short", and since the capability is there, why not take advantage of it??

Nobody makes a revolver properly "scaled" for the 9mm, they are all on .38 frames. But, that's mostly economics. There simply isn't enough demand for 9mm revolvers to justify the cost of making its own frame size...

You CAN fit revolver length rounds into semi autos. You can fit actual revolver rounds in semi autos. I have several, including .357 & .44 Mag semi autos. What you can't do is fit them in a small gun.
 
gwpercle said:
Most revolver rounds were developed when black powder was the propellant . It takes a much larger volume of black powder to push a bullet to usable velocities.
To make more powerful rounds the case would be made longer and then longer.
Black powder 38 Short Colt was extended to get the 38 Long Colt which was extended to get the 38 special....this is when smokeless powder started replacing black powder but no going back now...the 38 Special was extended to make the 357 Magnum.

No semi-automatic rounds were ever , to my knowledge, developed and loaded with black powder...smokeless powder allowed the use of the short rimless cases .

Although you may be making your answer up...it's correct !
Smokeless powder allowed short cases and black powder required the long case.
Gary
Click to expand...

Yes! It's been a while since I guessed right! :p

By the way, I have read that the .357 Magnum actually didn't require a yet-longer case than the .38 Special. Apparently they did it for safety reasons, to keep people from putting them into .38 revolvers. (On the other hand, we could name other hopped-up cartridges that are dimensionally identical to their weaker ancestors.)
 
COSteve said:
In addition to the above, the primary reason that semi-auto brass is short is that people's hands are only so big so it limits how big the grip can be. As the mag slides up the grip in all but a few (Broomhandle Mauser C96 comes to mind as one that doesn't) the length of the rd is restricted to what will fit into a grip people can use.
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Great point. I've fondled an FN Five-seveN. That's a lot for my hands.

On the other hand, that explanation better demonstrates why auto cartridges need to be relatively short. I wasn't certain why revolver cartridges were so freaking long.
 
44 AMP said:
Nobody makes a revolver properly "scaled" for the 9mm, they are all on .38 frames. But, that's mostly economics. There simply isn't enough demand for 9mm revolvers to justify the cost of making its own frame size.
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Different topic, but rimless ammunition in a revolver makes no sense to me. I dunno if I'd wanna mess with moon clips.
 
Both the .357 (in 1935) and the .44 Mag about 20 years later were developed from "overloading" the shorter parent cases (.38 & .44 SPL) There was enough space in the shorter cases for the magnum powder charges and pressure, but in most guns made for the Specials that would be a very, very bad idea.

The cases were lengthened, approx. 1/8" so they would not chamber in weaker guns made for the lower pressure Specials.

Here's a tidbit, the reason we have a .44 Magnum is because of the guns in existence when Elmer Keith was experimenting. He started heavy loading the .45 Colt, but after blowing up a few (3, anyway..) he switched to the .44 cal, because with the guns he could get at the time, the smaller .44 had enough more steel in the cylinder (vs the .45) to take the pressures he used creating his "magnum" loads.


Different topic, but rimless ammunition in a revolver makes no sense to me.
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Ever hear of the 9mm Federal??

it was a rimmed 9mm Luger case, made for revolvers. Didn't last long, not enough market. Both the gun and the rounds are kind of collectors items now, I think.

And, rimless cases work great in my Single Action revolvers, no clips needed for them. :D
 
44 AMP said:
Ever hear of the 9mm Federal??



it was a rimmed 9mm Luger case, made for revolvers. Didn't last long, not enough market. Both the gun and the rounds are kind of collectors items now, I think.
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Actually, I have. I stumbled across references to it a few years ago when I was researching the possibility of a getting a 9mm revolver. I ditched the idea.



44 AMP said:
And, rimless cases work great in my Single Action revolvers, no clips needed for them. :D
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OK, I'll bite: How does it headspace?
 
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Rare tidbit, the Smith& Wesson model 547 was a 9mm Luger revolver. Not taking moonclips for ejection.
Smith patented a special star extractor for ejection.
It works decently.
The guns were made for a French police contract, that they backed out of.
Fun K frame.
 
74A95 said:
They headspace on the case mouth, just like in a semiauto. It's just a matter of reaming the chamber to the correct depth.
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That’s exactly what I’d want in a modern revolver. In 9mm or .45 Auto.
Ya know Indiana Jones carried an M1917 .45 ACP revolver. Some of those had “stepped” chambers that headspaced on the casing mouth.
Still not clear to me how to eject the cases, though. I’d have to see it work.
 
74A95 said:
As 44 amp noted, they are used in a single action revolver. That's the key. They are ejected one at a time, manual, just like the regular rimmed ammo.
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Sorry, I was referring to a double-action revolver with chambers that headspace off the case mouths. I think the S&W M1917 revolver was that way. I just dunno how you get the casings out.

The more I think about this, I think it stands to reason that revolver rounds and auto rounds don’t cross over much.
 
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Brownstone322 said:
Sorry, I was referring to a double-action revolver with chambers that headspace off the case mouths. I think the S&W M1917 revolver was that way. I just dunno how you get the casings out.
The more I think about this, I think it stands to reason that revolver rounds and auto rounds don’t cross over much.
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Moonclips. Seriously, why think about getting unmoonclipped rimless cases out since no one does that in double action guns, except the exception noted by 105kw.
 
You can get 45 auto out of the cylinder without moon clips. I’ve never had them stick so much I needed a dowel to push them. That said I usually load 45 auto rim for the 1917.
 
a double-action revolver with chambers that headspace off the case mouths. I think the S&W M1917 revolver was that way.
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The S&W 1917s were all made to headspace off the case mouth, and could be used without the half moon clips. Clips made extraction convenient, but were not a necessity, as empties can be picked out with a fingernail, or poked out with a pencil (or a loaded rifle round).

From what I understand, the first batch of Colt 1917s had cylinders that were bored straight through, and required the clips to headspace properly. this turned out to widely unpopular and follow on batches of Colts had cylinders with a the step for case mouths to headspace on.

It also appears that the first batch of Colt 1917s were re-worked after WW I, and had their cylinders replaced with the usual stepped kind, though I have found no proof, it seems likely.

The .45 Auto Rim case was created in the 20s by the Peters company, to give civilian owners of surplused 1917s a round that didn't need the clips for regular ejection.
 
FWIW Charter Arm's Pitbull is chambered in 9mm, 40 S&W and 45 ACP. It doesn't use moonclips and works surprisingly well.
 
"...limits how big the grip can be..." Yep. You really need to try a Desert Eagle on for size to appreciate that too.
They're not only descendants of BP cartridges, they are BP cartridges. BP is loaded by volume. Needs more space.
Indiana Jones carried a prop gun that looked like an M1917. He also carried an Inglis BHP that didn't exist at the time portrayed in the Lost Ark. One must remember that what you see in movies is not real.
 
105kw said:
Rare tidbit, the Smith& Wesson model 547 was a 9mm Luger revolver. Not taking moonclips for ejection.
Smith patented a special star extractor for ejection.
It works decently.
The guns were made for a French police contract, that they backed out of.
Fun K frame.
Click to expand...
Remember the 9mm Federal , a rimmed 9mm Luger case that was developed for those French revolvers....It was going to be a great idea until someone realized those high pressured 9mm Federal rounds fit perfectly into the low pressure 38 S&W Top Break revolvers that are still around....Lawyers nixed that little project real fast .
Do a search on 9mm Federal for the complete story...it's interesting .
Gary
 
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