10mm Auto In Revolvers?

By Chuck Hawks

10mm Auto
Illustration courtesy of Hornady Mfg. Co.

There seems to be a mini-compulsion among handgun manufacturers to offer autoloading pistol cartridges in revolvers. Off hand, I can think of various revolvers, past and present, chambered for 9x19mm, .40 S&W, .45 ACP and 10mm Auto.

For example, one of the cover stories in the October 2018 issue of Shooting Times magazine focused on the 10mm Auto cartridge being offered in the giant Ruger Super Redhawk revolver (54 ounces empty with a 6.5" barrel), which was designed for the .454 Casull, but is also available in .480 Ruger, .44 Magnum and .41 Magnum. (The 10mm Glock 40 MOS weighs 28.15 ounces empty with a 6" barrel.) Ruger also currently offers the 10mm cartridge as a distributor exclusive in the medium frame GP100 revolver, which was designed for the .357 Magnum.

As most regular Guns and Shooting Online readers are probably aware, I am a fan of the 10mm Auto cartridge. It is, in fact, my favorite autoloading pistol cartridge, as it is the only relatively common auto pistol cartridge useful for hunting Class 2 game, as well as personal protection.

Unlike most autoloading pistol cartridges from the .25 ACP to the .45 ACP, which are stubby little things with restricted powder capacity, the 10mm Auto has a comparatively roomy case. It is as close as auto pistols get to the .357 Magnum revolver cartridge, which I still consider the finest all-around handgun cartridge on the planet.

However, as useful as the 10mm Auto is in semi-automatic pistols, particularly those like the long slide Glock 40 MOS and SIG P220 Match Elite, it is redundant in revolvers. The 10mm Auto is ballistically inferior to the established .357 Magnum, .41 Magnum and .44 Magnum cartridges, all of which were designed specifically for use in revolvers. (They have also been adapted to lever action carbines.)

Ballistically, pretty much anything the 10mm Auto can do the .357 Magnum can do slightly better. (See Compared: The .357 Magnum and 10mm Auto for more on this.) The 10mm (a .40 caliber cartridge) is clearly inferior to the .41 and .44 Magnums in every way.

Using a rimless, straight wall case, like most auto pistol cartridges, the 10mm headspaces on its case mouth. This is a less secure and less precise method of headspacing than the rimmed cases used by traditional revolver cartridges. It also makes the 10mm Auto more finicky to handload than revolver cartridges.

The under barrel ejector rod of single action revolvers can easily punch out fired 10mm cases, but the star ejector of double action revolvers cannot eject rimless 10mm cases unless "half moon" adaptors are used. Not only are these little sheet metal adaptors rare, easily lost and an additional expense, especially in 10mm Auto caliber, they must also be loaded prior to being inserted in the revolver. This increases loading time and complexity and negates one of the real advantages revolvers have over auto pistols; i.e. simple and direct loading of cartridges straight from the box without the need for pre-loading magazines, clips, or the like.

Full power 10mm cartridges kick less than full power .357 or .44 Magnum revolver cartridges, but this is negated by the fact that any .357 or .44 Magnum revolver can also shoot mild .38 Special or .44 Special cartridges. In reality, there isn't anything the 10mm Auto can do in a revolver that a revolver cartridge cannot do better, so what is the point?

Note: A full length article about the 10mm Auto cartridge can be found on the Handgun Cartridges page.

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Copyright 2018 by Chuck Hawks. All rights reserved.