Why Calibers 'become' Semi or Revolver
- Thread starter maustypsu
- Start date
Extraction and feed
Revolvers use extractors that grab a rim that extends past the diameter of the case. Traditional revolver ammo has such rims.
Rims that extract past case diameter don't feed well into magazines; as round count goes up, the magazine has to curve in order to accommodate the stacking of rims. Traditional auto ammo is "rimless." The rim is the same diameter as the casing, but the end of the casing that meets the rim is indented, so the auto's extractor can gain purchase.
The revolvers out there designed for traditional auto rounds have cylinders cut to allow the use of moon or half-moon clips, which give the revolver's extractor a means to engage "rimless" rounds.
Revolvers use extractors that grab a rim that extends past the diameter of the case. Traditional revolver ammo has such rims.
Rims that extract past case diameter don't feed well into magazines; as round count goes up, the magazine has to curve in order to accommodate the stacking of rims. Traditional auto ammo is "rimless." The rim is the same diameter as the casing, but the end of the casing that meets the rim is indented, so the auto's extractor can gain purchase.
The revolvers out there designed for traditional auto rounds have cylinders cut to allow the use of moon or half-moon clips, which give the revolver's extractor a means to engage "rimless" rounds.
Could you give an example of what you mean? Revolvers function best with
rimmed cases, while semiautomatics function best with rimless cases. Hence we have 45 Long Colt and 45 ACP. 38 Special in revolvers, 9MM Parabellum in
semiautomatics. 32 S&W (or Colt if you prefer), 32ACP. About the only caliber I can think for a semiautomatic that has no revolver equivalent is 25ACP.
rimmed cases, while semiautomatics function best with rimless cases. Hence we have 45 Long Colt and 45 ACP. 38 Special in revolvers, 9MM Parabellum in
semiautomatics. 32 S&W (or Colt if you prefer), 32ACP. About the only caliber I can think for a semiautomatic that has no revolver equivalent is 25ACP.
That's what I mean
I guess I'm thinking both .22 and 9MM have semi and revolver versions.
Why couldn't we have more like that? I guess the answer above about the rim size answers the question.
But both of these calibers seem to work so I was wondering why we don't have more.
I guess I'm thinking both .22 and 9MM have semi and revolver versions.
Why couldn't we have more like that? I guess the answer above about the rim size answers the question.
But both of these calibers seem to work so I was wondering why we don't have more.
Because concessions have to be made in order to shoehorn them into a different platform.
It's tremendously difficult to reliably feed a rimmed cartridge through a double stack magazine.
Notice how few double-stack .22 lr magazines there are. And the few that are available still have severe problems.
And for a revolver, you need something special like moon clips or some sort of weirdo mechanism like this:
http://www.charterfirearms.com/products/CARR.html.
It's just so much easier to simply chamber a firearm in a more appropriate cartridge.
It's tremendously difficult to reliably feed a rimmed cartridge through a double stack magazine.
Notice how few double-stack .22 lr magazines there are. And the few that are available still have severe problems.
And for a revolver, you need something special like moon clips or some sort of weirdo mechanism like this:
http://www.charterfirearms.com/products/CARR.html.
It's just so much easier to simply chamber a firearm in a more appropriate cartridge.
Mike Irwin
Staff
"I guess I'm thinking both .22 and 9MM have semi and revolver versions."
Beg your pardon?
I can't think of a single rimless .22 used in semi-auto pistols. It would, by nature, have to be a centerfire.
The only rimmed 9mm I can think of was the VERY short-lived 9mm Federal, which died a very messy death with the failure of Charter Arms, the only company ever to offer a gun for it.
If, however, you don't mean different versions of the cartridges, any number of traditionally revolver or semi-auto cartridges have "crossed over" with varying degrees of success, including .25 ACP, .38 Special, .40 S&W, 10mm, .357 Magnum, .41 Magnum, .44 Magnum, .45 ACP, and .50 AE.
Beg your pardon?
I can't think of a single rimless .22 used in semi-auto pistols. It would, by nature, have to be a centerfire.
The only rimmed 9mm I can think of was the VERY short-lived 9mm Federal, which died a very messy death with the failure of Charter Arms, the only company ever to offer a gun for it.
If, however, you don't mean different versions of the cartridges, any number of traditionally revolver or semi-auto cartridges have "crossed over" with varying degrees of success, including .25 ACP, .38 Special, .40 S&W, 10mm, .357 Magnum, .41 Magnum, .44 Magnum, .45 ACP, and .50 AE.
carguychris
New member
The answer is simple: poor sales.
As previously mentioned, rimmed cartridges inherently work poorly in semi-auto magazines unless capacity is severely limited. A few pistols have been offered in high-powered "revolver" calibers such as .357Mag and .44Mag, but they have tended to be large and heavy with limited capacity. This has severely limited their marketing appeal because they essentially have no advantages over a revolver.
A few revolvers have been offered in .45ACP and 10mm Auto, but they typically sell poorly compared to equivalent models in .357Mag, .44Mag, or .45 Colt. They're offered for two basic reasons: 1) competitors in action-oriented pistol competition like them because moon clips allow faster reloading, and 2) revolver collectors will buy small numbers of just about anything, and it doesn't cost a revolver manufacturer very much to rechamber a gun, so selling a small run for collectors- say 400-500 guns in a particular caliber- can be a moneymaking proposition. It costs a whole lot more to rechamber a semi-auto because of the engineering required to ensure that the rounds cycle and feed properly.
The market for semi-auto pistols in lower-powered revolver calibers such as .32 Long and .38Spl is inherently limited because these calibers don't offer any real-world ballistic advantages over lower-powered semi-auto rounds such as 9mm Luger and .32ACP. A semi-auto pistol chambered for these cartridges would essentially combine the worst of both worlds.
Same goes in reverse for a revolver in a low-powered semi-auto caliber- why bother when an existing round will do the same thing? Two footnotes:
A few semi-autos that have been offered in low-powered revolver calibers, but they have been tailored towards competetive target shooters who are required to use these calibers by the rules of the competitive sanctioning body. A semi-auto gives a shooter an advantage in traditional Bullseye- or Olympic-style pistol competition because only one hand may be used to manipulate the gun, requiring the shooter to reset his or her grip to manually thumb-cock a revolver, thereby making "rapid-fire" stages more difficult. The stages are limited to 5 rounds so high mag capacity is not important.
Every couple of months or so, someone starts a thread asking why no gunmaker has designed a .380ACP or 9mm revolver that takes advantage of the shorter cartridge length to shorten the overall length of the gun for CCW. The reason is simple IMHO: the main problem with concealing a revolver is the width of the cylinder, not the overall length of the gun. A gunmaker designing such a firearm would be taking a major risk engineering and producing a special extra-short frame to solve a largely non-existent problem.
The main reasons are rims and overall cartridge length. As has been pointed out, the rims and relatively long overall length of most popular revolver cartridges represent significant challenges to reliable operation and compactness of automatic firearms. Most revolver cartridges are rimmed either because they were developed before the widespread popularity of automatic firearms (examples include .38 Special, .44 Special, and .45 Long Colt) or they were developed on such a cartridge (examples include .357 Magnum, .44 Magnum, and .454 Casull). Likewise, many revolver cartridges are relatively long because they were either developed before the advent of smokeless powder (black powder requires a much larger volume and thusly more case capacity) or were developed on such cartridges. While it is not particularly difficult to get the shorter, rimless auto cartridges to work well in a revolver, they often don't offer significant advantage over other cartridges that are already well established in that particular platform and thusly aren't typically very popular. One notable exception to this is .45 ACP, but I suspect that had the military not insisted that Colt and S&W modify their revolvers to use this cartridge during WWI the .45 ACP would be almost exclusively chambered in semi-automatics. Another is .22 Long Rifle, but this cartridge is extremely popular in both handguns and rifles of all action types.
azredhawk44
Moderator
Mike, you're reading to deeply.
He's not talking about different versions of .22 and 9mm cartridges, he's talking about those same cartridges being chambered for both revolvers and autos.
maustypsu:
Revolver cartridges initially got their design characteristics back in the 19th century. The rim was put on them to control the depth of chambering (headspace), and they were typically about 1.6-1.7 inches long for two reasons:
1. The cylinder needed to be that long so the gases from the forcing cone wouldn't burn the shooter's finger as he pulled the trigger, and;
2. The black powder available at the time needed that much case capacity in order to give sufficient power.
I don't know a lot about turn of the century cartridges, but two of the earliest that are still with us today are the .380 ACP (automatic colt pistol) and the .45 ACP (automatic colt pistol).
These cartridges are shorter than their revolver oriented counterparts (.38 Long Colt and .45 Colt), but due to improvements in powder technology they were equally powerful.
The rims were taken off these cartridges because rims cause a situation called "rim lock" when you stack rimmed cartridges one atop the other. That's why you see very few automatic firearms using rimmed cartridges.
As far as rimless cartridges in revolvers... it makes extraction tricky. Especially in modern double action revolvers that use a central extraction star rather than the old style single action revolvers that use a single chamber extractor.
You can chamber a revolver for 9mm, .40 or .45acp. There's a member here that took a S&W 442 (I think... it's a smith .38 snub at least) and had the cylinder face cut for 9mm moonclips and also reamed the chambers to headspace the cartridge off the mouth rather than on the old style .38 rims. You can take a S&W model 610 and shoot either .40 or 10mm automatic cartridges with the aid of moonclips. And S&W has been making the models 25 and 625 for ages, which shoot .45acp with moonclips, or .45 auto-rim which is identical to an acp case but with a rim attached to it to avoid the need for moonclips.
You see some crossover in autos, too.
Coonan and Grizzly made 1911's chambered in .357 magnum as well as other rimmed cartridges.
The Desert Eagle is most famously chambered in .50AE, but also in .357 magnum and .44 magnum.
But, what you typically see is a preference for revolvers to have rims, and autos to be rimless. For example, the .44 AutoMag. The idea was for an automatic .44 magnum single action handgun... but it was just easier to get rid of the rim, so you ended up with ammo like this:
It's a .308 winchester rifle cartridge cut down and flared out to fit .44 bullets. Rimless, since it goes in an auto. You'll notice the lack of a supertight crimp at the case mouth... that's because auto cartridges have a design preference to headspace off that little lip of brass at the mouth rather than off of a rim at the base of the cartridge.
There's always exceptions to the rule, but rimmed cartridges tend to go in revolvers and rimless cartridges tend to go in autos because of the way they are designed to work.
Clear as mud?
He's not talking about different versions of .22 and 9mm cartridges, he's talking about those same cartridges being chambered for both revolvers and autos.
maustypsu:
Revolver cartridges initially got their design characteristics back in the 19th century. The rim was put on them to control the depth of chambering (headspace), and they were typically about 1.6-1.7 inches long for two reasons:
1. The cylinder needed to be that long so the gases from the forcing cone wouldn't burn the shooter's finger as he pulled the trigger, and;
2. The black powder available at the time needed that much case capacity in order to give sufficient power.
I don't know a lot about turn of the century cartridges, but two of the earliest that are still with us today are the .380 ACP (automatic colt pistol) and the .45 ACP (automatic colt pistol).
These cartridges are shorter than their revolver oriented counterparts (.38 Long Colt and .45 Colt), but due to improvements in powder technology they were equally powerful.
The rims were taken off these cartridges because rims cause a situation called "rim lock" when you stack rimmed cartridges one atop the other. That's why you see very few automatic firearms using rimmed cartridges.
As far as rimless cartridges in revolvers... it makes extraction tricky. Especially in modern double action revolvers that use a central extraction star rather than the old style single action revolvers that use a single chamber extractor.
You can chamber a revolver for 9mm, .40 or .45acp. There's a member here that took a S&W 442 (I think... it's a smith .38 snub at least) and had the cylinder face cut for 9mm moonclips and also reamed the chambers to headspace the cartridge off the mouth rather than on the old style .38 rims. You can take a S&W model 610 and shoot either .40 or 10mm automatic cartridges with the aid of moonclips. And S&W has been making the models 25 and 625 for ages, which shoot .45acp with moonclips, or .45 auto-rim which is identical to an acp case but with a rim attached to it to avoid the need for moonclips.
You see some crossover in autos, too.
Coonan and Grizzly made 1911's chambered in .357 magnum as well as other rimmed cartridges.
The Desert Eagle is most famously chambered in .50AE, but also in .357 magnum and .44 magnum.
But, what you typically see is a preference for revolvers to have rims, and autos to be rimless. For example, the .44 AutoMag. The idea was for an automatic .44 magnum single action handgun... but it was just easier to get rid of the rim, so you ended up with ammo like this:
It's a .308 winchester rifle cartridge cut down and flared out to fit .44 bullets. Rimless, since it goes in an auto. You'll notice the lack of a supertight crimp at the case mouth... that's because auto cartridges have a design preference to headspace off that little lip of brass at the mouth rather than off of a rim at the base of the cartridge.
There's always exceptions to the rule, but rimmed cartridges tend to go in revolvers and rimless cartridges tend to go in autos because of the way they are designed to work.
Clear as mud?
armsmaster270
New member
Smith & Wesson made their 38Spl wadcutter only Auto I think the Mod 52
tailgunner6
New member
Colt also offered their Gold Cup National Match in .38 Special (wadcutter only). As a result of the rimmed cartridge, both guns' magazines only hold a maximum of 5 rounds.
carguychris
New member
You're correct, it was called the Model 52 Shooting Master, although many collectors refer to it as the 52-2 since the "-2" engineering variant was the only one mass-produced for sale to the general public. The M52-2 was a modified and highly accurized version of the 9mm Model 39. Like the Colt Gold Cup National Match, it held 5 .38Spl flush-seated wadcutters.
Both of these guns are examples of what I talked about in my earlier post: special guns tailored to rapid-fire Bullseye competition. (AFAIK "rapid-fire" in Bullseye is 2 seconds between shots, not exactly rapid-fire by IDPA standards, but rapid enough that cocking a DA revolver one-handed between shots can be a serious impediment.) Both guns were slow sellers and are coveted collector's items today.
An earlier experimental Model 52 was produced for the US Army Advanced Marksmanship Unit chambered for a special cartridge called the .38 AMU, which was basically a semi-rimless .38Spl. IIRC Colt produced a kit to convert the Gold Cup National Match to use this cartridge. The cartridge itself, the original .38 AMU S&W Model 52, and converted Colts are very rare and valuable collector's items today.
john in jax
New member
Here is a pic/example (off the web) of what the base of your common semi-auto cartridge looks like.
"Rims that extract past case diameter don't feed well into magazines; as round count goes up, the magazine has to curve in order to accommodate the stacking of rims. Traditional auto ammo is "rimless." The rim is the same diameter as the casing, but the end of the casing that meets the rim is indented*, so the auto's extractor can gain purchase."--MLeake
*Known as the "extractor groove", to distinguish from "Rimmed" rounds.
There are also "semi-rimmed" cartridges;the .38 Super comes to mind, where the case head is slightly wider than the cartridge case.
There have even been attempts to utilize "rebated rims", where tht case head is of smaller diameter than the cartridge case. These rounds are an attempt to fire larger calibers from pistols of a given caliber, with only having to change the barrel and magazine.
The .41 Action Express was the best known. It was an attempt to convert 9mm pistols to fire .40 cal rounds, simply by changing barrels. The case head was the same diameter as a 9mm cartridge. The advent of the .40S&W killed the cartridge, though brass may be available through specialty makers
*Known as the "extractor groove", to distinguish from "Rimmed" rounds.
There are also "semi-rimmed" cartridges;the .38 Super comes to mind, where the case head is slightly wider than the cartridge case.
There have even been attempts to utilize "rebated rims", where tht case head is of smaller diameter than the cartridge case. These rounds are an attempt to fire larger calibers from pistols of a given caliber, with only having to change the barrel and magazine.
The .41 Action Express was the best known. It was an attempt to convert 9mm pistols to fire .40 cal rounds, simply by changing barrels. The case head was the same diameter as a 9mm cartridge. The advent of the .40S&W killed the cartridge, though brass may be available through specialty makers
Crimping
Revolver cartridges are roll crimped versus auto cartridges being taper crimped. (General rule.)
For example:
.45 auto headspaces with the case and taper crimping the bullet allows adequate pressure to build, but not too much pressure which would be possible with roll crimping.
.44 mag uses roll crimping, more secure, to avoid bullet movement from recoil.
Addition/Edit: This is a very simple and general explaination. More to it, just am not going to go into all of the detail; and some might/do debate the degree of crimping/necessity of crimping/etc...
More examples:
roll crimping a .45 auto can also lead to failure to feed properly.
single shot "paper punching" (not using the magazine/or completely loading the cylinder) is debated whether or not crimping is necessary or useful.
A consistent crimp can aid in consistantcy/accuracy.
Revolver cartridges are roll crimped versus auto cartridges being taper crimped. (General rule.)
For example:
.45 auto headspaces with the case and taper crimping the bullet allows adequate pressure to build, but not too much pressure which would be possible with roll crimping.
.44 mag uses roll crimping, more secure, to avoid bullet movement from recoil.
Addition/Edit: This is a very simple and general explaination. More to it, just am not going to go into all of the detail; and some might/do debate the degree of crimping/necessity of crimping/etc...
More examples:
roll crimping a .45 auto can also lead to failure to feed properly.
single shot "paper punching" (not using the magazine/or completely loading the cylinder) is debated whether or not crimping is necessary or useful.
A consistent crimp can aid in consistantcy/accuracy.
Last edited: