120px-10MM AUTO - FMJ - 2
10mm Auto
Country of origin

USA; Sweden


LtCol. Jeff Cooper, USMC (Retired); Norma Precision

Year production began


Cartridge type

Rimless, Straight

Parent cartridge

.30 Remington

Overall length

32 mm (1.26 in)

Case length

25.20 mm (.992 in)

Neck diameter

10.70 mm (.421 in)

Base diameter

10.81 mm (.426 in)

Rim diameter

10.85 mm (.427 in)

Rim thickness

1.40 mm (.055 in)

Rifling twist


Primer type

Large pistol

The 10mm Auto (10x25mm) is a handgun cartridge introduced by the Swedish ammunition manufacturer Norma in 1983.


It was designed at the behest of Dornaus & Dixon Enterprises, the firm that introduced the Bren Ten pistol; this pistol was intended as a military, police and self defense combat style pistol. In response to many who wished for a caliber to bridge the gap between the 9mm Luger (a small but fast cartridge) and the .45 ACP (a slow but big cartridge), the 10x25mm round was developed concurrently with the Bren Ten to be an ideal solution in the service handgun market. 10mm Auto was necked down from the rifle cartridge, .30 Remington, the rimless version of the .30-30 Winchester.

Manufacturing problems plagued Dornaus & Dixon; guns were shipped without magazines due to mistakes by the magazine contractor, and slides were known to fracture when shooting. Only about 1500 guns were shipped before D&D went out of business in 1986.

Colt saved the cartridge from extinction by developing the Delta Elite, a beefed up M1911 chambered in 10mm. The high pressure and muzzle energy of the newer cartridge sometimes caused the area above the slide stop hole in the frame to crack due to the thinness of the metal at that spot. This combined with the Bren Ten's problems gave the 10mm a reputation for being so powerful as to damage the weapons that fired it. The problem in the Delta Elite was solved by simply removing the bit of metal prone to breakage, leaving a small gap in the frame rail. It has since been discontinued, though its reintroduction was announced at the 2008 SHOT Show.

Glock GmbH Inc. was the only notable manufacturer to produce a 10mm during much of the 90s with their full size Glock 20 and subcompact Glock 29, which are still in production today.

The 10mm has been mostly supplanted by the .40 Smith and Wesson, a 10x22mm cased cartridge that uses a .401 caliber projectile, similar to the 10x25mm. This round was developed after F.B.I. ballistic gelatin testing revealed that a low velocity 10mm projectile achieved ideal penetration results with less recoil, blast, and wear and tear on duty weapons. Ammunition manufacturers slowed down their 10mm rounds to match the F.B.I. load. Smith and Wesson realized that the slower round did not require as much gunpowder, and could use a shorter case. Using a small primer versus the 10mm's large primer allowed the .40 S&W to fit in smaller, more manageable 9x19mm-size handguns. The smaller platform and lighter recoil energy made the .40 S&W an extremely successful cartridge, eclipsing its parent round, the 10mm Auto. As a result, the 10mm Auto has gained notoriety for being the round that was too powerful for the FBI.

The 10mm has seen a comeback of sorts in the 21st century with Tanfoglio, Dan Wesson CZ, Kimber, Colt, and GLOCK all producing models in 10mm, and continues to have a devoted, if small following in the handgun community.

Design DetailsEdit

10mm hollowpoints run from 135 to 200 grains with 200-230 grain lead bullets not unheard of. Muzzle velocity can range from ~900 feet per second to over 1600 feet per second in full size barrels and full power loads.

10mm fires optimally in a barrel with 1/15 rifling twist, and fires with a maximum pressure of 37,500 psi (2586.2 bar).

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