Key Point: The 10mm Auto round is a technical success.

One of the most powerful semi-automatic handguns is also from one of the oldest firearms manufacturers in America.

The Colt 10mm Delta Elite Rail combines the 10mm Auto cartridge with the 1911 pistol platform, all offered up by a company that made its name selling cavalry revolvers during the Civil War.

Established in 1836 by inventor Samuel Colt, one of the company’s earliest successes was the Walker. Named after a U.S. Cavalry officer engaged in the Mexican-American War, the large, powerful revolver was the result of a request by Walker for a cavalry sidearm. Walker wanted a large pistol that could be carried in one hand while the other held the reigns of a horse. The Walker was so successful it led to a successor, the Colt Dragoon.

More than 150 years later, Colt again developed a powerful, large caliber handgun--this time a semi-automatic pistol.

The Colt Delta Elite, released in 1989, used the modern equivalent of the Dragoon’s .44 ball round, 10mm Auto. The Delta Elite is a modified 1911-type handgun—the Colt Series 80—rechambered for 10mm (roughly .40 caliber).

The 10mm Auto round is the heart of the Delta Elite. Invented by gun scholar and author Jeff Cooper, 10mm Auto was an attempt to create a 200 grain bullet capable of supersonic speeds. (The .45 ACP round, which Cooper was a strong proponent of, is typically a 230 grain round traveling at high subsonic speeds.)

Instead of using .45 caliber, which would have made an already powerful recoil even worse, Cooper went down a notch to 10mm, creating the 10mm Auto.

The 10mm Auto round was a technical success. Most 10mm Auto rounds weighing 180 grains or less have a velocity that easily exceeds 1,125 feet per second at sea level, while packing a muzzle velocity of 425 foot-pounds or higher.

A wide variety of ammunition loads have been developed for the 10mm Auto platform with some achieving a muzzle velocity of Mach 2, or twice the speed of sound, and up to 1,015 foot-pounds of energy.

The Delta Elite is still one of the most popular 10mm Auto platforms. Patterned after a full-sized 1911A1 pistol, the Delta Elite Rail has a five inch barrel, an eight round magazine, and single action, hammer-fired operating system. This allows the Delta Elite to be carried in what Jeff Cooper referred to as “Condition One”: gun loaded, round in the chamber, hammer cocked back, and manual safety engaged. Once drawn, a Delta Elite carried Condition One need only have its manual safety disengaged to fire with a light trigger pull.

The Delta Elite Rail sports several other features the notoriously conservative 1911 crowd has grown to accept. The pistol features a beavertail grip safety, skeletonized hammer, and reduced weight trigger. Aiming is via a set of Novak low profile, high visibility three dot sights.

The pistol gets its name from a Picatinny rail mounted underneath the government-sized barrel, allowing for the mounting of weapon lights and laser aiming devices.

The Delta Elite, like any 10mm Auto pistol, is not for everyone. The FBI embraced the caliber after the infamous 1986 Miami shootout, when two criminals armed with a .223 rifle, .357 Magnum, and shotgun managed to kill two federal agents and wound another five, all the while sustaining multiple injuries from FBI-issued .38 Special revolvers. The FBI, overcorrecting to emphasize lethality, later backed off the 10mm Auto cartridge concluding it generated an excessive amount of recoil.

Today Colt advertises the Delta Elite Rail as a backup handgun for large game hunters, capable of putting down charging boar or other dangerous game. Alternately Colt says the gun is suitable for “advanced security operatives”, where “advanced” is likely a function of upper body strength and pistol experience.

The 10mm Auto caliber is one of the few ported over to the 1911A1 platform, and the Delta Elite Rail is one of the few pistols in 10mm Auto. While the caliber will never find the success of Nine-millimeter Luge or even .45 ACP, the Delta Elite Rail serves a die-hard cadre of high powered semi-automatic pistol enthusiasts.

Kyle Mizokami is a defense and national-security writer based in San Francisco who has appeared in the Diplomat, Foreign Policy, War is Boring and the Daily Beast. In 2009 he cofounded the defense and security blog Japan Security Watch. You can follow him on Twitter: @KyleMizokami. This article first appeared in 2019 and is reprinted here due to reader interest.

Image: Wikimedia Commons