In 1983, the 10 mm semi-auto pistol cartridge made its debut. Developed by Jeff Cooper as a more powerful man stopper, the new cartridge was originally paired with the "Bren 10" pistol designed by Michael Dixon and Thomas Dornaus.

Both the cartridge and the handgun generated plenty of excitement in the shooting community at the time. Unfortunately, the Bren 10 ran into production problems that limited it to a small 1,500 unit run of between 1983 to 1986. Despite the failure of the first pistol chambered for the potent 10 mm, the enthusiasm for the cartridge was still strong enough to induce Glock to step in and develop a shooting solution based on its pistol design.

In order to handle the 10 mm cartridge's increased length and pressure levels, the G20 is about 0.10-inches wider and 0.13-inches longer than most of the other Gen4 duty-size Glocks, including the G17 and G22 (the G21 chambered in .45 ACP uses the same frame as the G20).

The polymer frame keeps the unloaded weight to a reasonable 27.51 ounces. The gas-nitrate-treated steel slide is topped with polymer fixed sights, and the 4.61-inch barrel contains hexagonal rifling.

The extractor has a small, square extension that acts as a visual and tactile loaded chamber indicator, making it easy to check with the tip of the trigger finger (or thumb for left-handed shooters). Other safety features include a trigger safety, firing pin safety and a drop safety.

The G20's polymer frame is molded with a Picatinny compatible accessory rail. Because this is a full-size pistol frame, the rail is long enough to accept a variety of light and laser modules.

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Accuracy testing was conducted from a bench rest using five, five-shot groups fired into targets set at 25 yards. Some readers will be quick to notice one of the rounds used for formal accuracy testing was loaded with hard-cast, gas-checked lead bullets.

Glock warns against the use of soft-lead bullets in its factory barrels. This is because soft-lead bullets have been known to foul the rifling, which could in turn increase the pressures inside the barrel to an unsafe level. However, true hard-cast bullets, when properly lubricated, will not cause the problems of soft-lead bullets. That's why ammunition companies like Buffalo Bore, DoubleTap and Underwood Ammo provide hard-cast hunting rounds for use in polygonal rifling pistols like the Glock.

The accuracy of this pistol and ammunition combination was excellent. It's good to see full-size production pistols keep shot groups hovering around the 3-inch mark during formal testing. When target groups stay consistently under 3 inches, that's a positive sign.

The tightest five-shot group size of the test was 2.25 inches, produced by both the DoubleTap 230-grain WFNGC Hardcast round and the HPR HyperClean 180-grain jacketed hollow point. The DoubleTap load produced the best five-shot group average of 2.4 inches, followed by the HPR round at 2.5 inches and Federal's American Eagle 180-grain full metal jacket at 2.6 inches.

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For those shooters who are fans of full-size and big-bore handguns, the G20 is a marriage made in heaven. The flat-shooting 10 mm is among the most powerful of the common semi-auto pistol cartridges, providing Magnum-level stopping power for personal protection and hunting. The Glock pistol design is simple, rugged, reliable and can handle the increased pressure levels of the 10 mm cartridge with alacrity.