Developed in 1983 as a law enforcement cartridge and originally adopted by the FBI, the 10mm was designed to deliver exceptional stopping power in a smaller caliber than .45 ACP, and while 10mm sounds like a bullet that is just one little bitty millimeter larger than a 9mm, the 10mm packs a wallop that gave everyone pause because of its higher chamber pressures and heavier recoil; yes, less than a .45 ACP cartridge, but still a handful for many. It has something to do with Newton’s third law: “For every action, there is an equal and opposite reaction.”

The 10mm had a brief turn with the FBI as most agents found it too harsh of a round to handle. Similar complaints occurred in other sectors of law enforcement and the 10mm finally gave way to the most commonly used cartridge today, the .40 S&W. While a number of ammunition manufacturers produce the 10mm, including Federal, Remington, Winchester, Hornady and CorBon, the guns chambered for this high-power round have diminished over time, but Glock has managed to tame this wildcat with a full-size semi-auto that allows optimum firepower without some of the abuses of harsh recoil, making the 10mm a very viable cartridge for personal defense.

The Glock 20 was first introduced in 1990, some seven years after the cartridge debuted, and is available in the SF “Short Frame” version (tested), and in a ported barrel G20C version. The latter is ideal for competitive shooting. A 10mm is a big bullet (0.4 inches diameter) in a big cartridge case (1.25 inches), and is usually loaded in a 180-grain weight (the range is 135 to 200 grains). Comparatively, the 10mm dwarfs the popular semi-auto 9mm round that was once the darling of law enforcement, which still remains the standard U.S. military pistol cartridge.

Gun Details

Building a gun to make the 10mm manageable is no small feat, and the Glock 20 does this with both balance and heft. With a larger slide and receiver, the G20 SF weighs 27.51 ounces (empty) and measures 8.07 inches in overall length with a 4.61-inch barrel. It also has a standard capacity of 15 rounds, making this a real powerhouse on your hip.

Specifications for the G20 series show a factory trigger pull of 5.5 pounds and a length of pull (including the safety toggle) of 0.5 inches. Trigger reset, like all Glock models, is almost instantaneous, and a Glock will fire a chambered round even with the magazine removed, a feature that most in law enforcement endorse.

Standard features on the G20 include a rail on the dustcover, which accepts a variety of tactical lights, lasers, and combination laser/tactical light systems like the GTL 10, GTL 21/22 and GTL 51/52, as well as numerous other accessories.

Like all Glock models, the G20 is a striker-fired design utilizing the Glock Safe Action constant double-action design. When the slide is cycled, the firing pin is set in a half-cocked “safe” position (safety and trigger forward), and the gun can only be discharged by pulling the safety and trigger simultaneously to disengage the firing pin safety. Though some argue the wisdom of the trigger safety design, this system is especially handy if you are on the move or engaging multiple targets. As soon as pressure is relieved from the trigger, the gun returns to a safe condition. A third internal safety prevents the gun from discharging if it is dropped. This is a very deliberate design since a Glock has no manual safety or external hammer to decock.

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