Revolvers that take moon clips for an inferior semi auto round. What's the point? Get a 357 and if you want less recoil shoot 38s. I don't get why you would limit your rounds to 5-6 with a revolver in a semi auto cartridge when you can have more capacity and faster reloads with an actual semi auto gun. I love revolvers but revolvers that shoot what they are made to shoot. To me it's ridiculous.
I used to think this way, but I see some very real potential advantages to rimless cartridges in a revolver. I think what remains to be seen are revolvers that are really optimized for them.
First of all, I came to realize how awesome full moon-clips are. I can take forty of them loaded to a class and don't have to reload all day. The guys with Glocks have to stop every hour or two to stuff more rounds in their magazines. They would need 16 magazines to keep up and I haven't seen anyone bring that many to a class yet. Picking up brass is easy. It falls from the shooting position instead of being thrown all over and it falls in large bunches instead of individual cases. Reload speed with clips is faster than most people are with magazines. I will concede that magazines are faster for dumping large volumes of ammo, but I don't do that. I never shoot my revolvers with individual rounds anymore. I just don't have any reason to.
.38 and .357 Magnum are generally not optimized for handgun length barrels with smokeless powder. They are all I shoot from handguns and the only handgun cartridge I reload, and I'm pretty familiar with them. The .38 case was designed for black powder. It's excessively long for smokeless powder, especially at the SAAMI pressure limit for .38 Special and +P. If we forgo the low pressure limit (as with .38/44 and .357 Magnum) we still have excess case capacity unless we're using a bulky, heavily-deterred powder (like H110 for example). Those powders do indeed offer more velocity out of even the shortest barrels, but at terrible efficiency. The bottom line is we can achieve most of the performance of .357 Magnum from 4" and shorter barrels, with a shorter case, using a medium burn rate powder. What's more, there is evidence that the additional performance of the longer case and slower magnum powders does not offer any benefit in terminal performance and wound ballistics. Essentially, you don't get anything for all the magnumness other than flash, gas, and blast.
So now let's talk about where a cartridge case should headspace. The rim is a brilliant solution for single-shots and doubles. It creates a challenge stacked in magazines and clips, though one that can be overcome (Enfield and Coonan for examples). However, in a revolver cylinder, the rims increase the diameter of the circle of cartridges larger than it needs to be.
While most modern rifle cartridges headspace on the shoulder of the bottleneck case, H&H found a unique alternative to rims for straight-walled cases when they introduced a belted case. Most notably, Freedom Arms adopted a belted case (500 WE) to allow a fifty caliber cartridge to be chambered in a revolver that otherwise would not have fit five rounds of a rimmed fifty-caliber cartridge like 500 S&W. Belts headspace very simply like rims, but they waste less diameter in doing so.
Headspacing on the case mouth is popular for straight-walled rimless cartridges, and most of the autoloader cartridges use it. It is less suitable for revolvers, particularly high-recoil magnum revolvers where a good crimp on the case mouth is desirable to prevent crimp jump. Unlike an autoloader, there is no magazine wall to hold the bullets in.
Headspacing can also be achieved with a moonclip in the case groove. One of the perceived disadvantages of this is the need for a moonclip. Some revolvers so chambered do offer an alternative of headspacing on the case mouth without clips, though extraction requires a rod when a clip is not used. For me personally, I no longer see any advantage to not using a moonclip in any double-action revolver.
An advantage of available moonclips for popular autoloader cartridges is that they are thicker, fitting into the thicker case grooves on those cartridges. They are therefore more durable and hold the cases more stiffly.
What remains to come about are revolvers that are best optimized for these chamberings. Most revolvers are based on frames for long cartridges. The Korth Skyhawk is a notable exception. Perhaps revolvers don't really need short cylinders. Even though the advantages of longer cases, bulky charges of slow powder, and long, heavy bullets are questionable for most uses, the ability to accommodate long cartridges is one of the advantages of a revolver in comparison to a pistol with the magazine in the handgrip. In that case, we might need to adopt lengthened cartridges like 10mm Magnum to make the most of it. Revolver cylinder diameters are also sized for popular rimmed cartridges. So for example, if we chamber a revolver in 10mm, a six-round cylinder won't be any smaller than it would be for 44 Magnum unless the manufacturer produces a unique frame and cylinder size. Sometimes the fit happens to be better than others. S&W used their large N-frame for 10mm, whereas Ruger fit 6-rounds into the smaller GP100. If we look at 9mm revolvers, we see guns like the 986 and 929 whose cylinders are large enough to accommodate and equal number of chambers and the rims on .357.
As long as the cylinder is large enough to hold an equal number of rimmed cases, the advantages of rimless are few and the proposition is not very compelling. Unfortunately, there's just not enough interest in revolvers outside special purposes like competition and handgun hunting to drive demand for the only slightly different features and specifications that could make rimless cartridge chamberings more compelling.
