10 mm Auto

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10 mm Auto
Left to right: 9mm Parabellum, 7.62x25 Tokarev, .357 SIG, 10mm Auto, .40 S&W, .45 GAP, .50 Action Express
Type	Pistol
Place of origin	Sweden
Production history
Designer	FFV Norma AB
Designed	1984
Specifications
Case type	Rimless, straight
Bullet diameter	10.16 mm (0.4 in)
Neck diameter	10.74 mm (0.423 in)
Base diameter	10.8 mm (0.425 in)
Rim diameter	10.8 mm (0.425 in)
Rim thickness	1.4 mm (0.055 in)
Case length	25.2 mm (0.992 in)
Overall length	32 mm (1.26 in)
Primer type	Center-fire large pistol
Ballistic performance
Bullet weight/type	Velocity	Energy
175 gr JHP	1290 ft/s (~393 m/s)	649 ft·lbf (~883 J)
Test barrel length: 5.5 in Source: Winchester ballistics page

The 10 mm Auto is a powerful and versatile cartridge for semi-automatic pistols, developed by ammunition manufacturer FFV Norma AB of Åmotfors, Sweden, and introduced in 1983 in the ill-fated Bren Ten pistol. Although it was selected by the FBI for use on the field, it proved too powerful to handle by many of its employees and too large for smaller handed individuals. These issues led to the creation and eventual adoption by the FBI of a shortened version of the 10mm, known as the .40 Smith & Wesson. Although famous for its accuracy and stopping power, scarcity and high prices have made it a niche cartridge, with a small but enthusiastic group of supporters.

1 History
2 Performance
3 Usage
4 Synonyms
5 References
6 See also
7 External links

[edit] History

Colt 10mm Auto Delta Elite

10mm Auto

The 10 mm Auto cartridge was innovated by famous firearms expert Jeff Cooper. It was intended to be a medium velocity pistol cartridge with greater stopping power than the 9 mm Luger Parabellum and better ballistics (i.e., flatter trajectory, greater range) than the .45 ACP. When Norma designed the cartridge, at the behest of Dornaus & Dixon for their Bren Ten pistol (a strengthened variant of the CZ-75), they decided to increase the power over Cooper's original concept. The resulting cartridge, introduced in 1983, is very powerful, packing the flat trajectory and high energy of a magnum revolver cartridge into a relatively short, rimless cartridge for an automatic pistol.

Despite its supporters, it has generally failed to gain popularity because the full-powered loads have too much recoil and blast for many people's tolerances. Additionally, its reduced loads can be duplicated in smaller guns using the less expensive .40 S&W cartridge. However, although in its lighter loadings it is an exact duplicate of the popular .40 S&W cartridge, in its medium loadings with medium bullet weights it can equal or exceed the performance of the .357 Magnum. Likewise, it can also duplicate or exceed .45 ACP performance for equivalent bullet weights. With full-power loads and heavy bullets, it may be used as a deer or boar hunting cartridge.

The 10 mm fires its bullet at high velocity, giving it a less-curved flight path and less drop or rise above point-of-aim compared to many other handgun cartridges, and thus is often described as "flat-shooting." Its outside diameter is also somewhat smaller than the .45 ACP and therefore offers the potential for greater capacity in a comparably-sized magazine. These characteristics also allow it to be used as a sub-machine gun cartridge, with H&K offering their MP5 platform in the cartridge.

The 10 mm Auto has never had large-scale popularity; nonetheless many feel that it is an excellent cartridge. It earned a reputation for battering guns early on, but this was largely due to manufacturers attempting to simply rechamber a .45 ACP design for the 10 mm Auto. However, the .45 ACP works at a much lower pressure and velocity, and the frame and slide designed to handle the .45 ACP cannot handle the greatly increased forces of a 10 mm Auto without substantial strengthening. Later guns (most notably the Glock 20 and the Smith & Wesson 1006) were built around the 10 mm and, if properly cared for, would work reliably for many years and thousands of rounds.

Another issue with early acceptance was the result of manufacturing problems with the Bren Ten; the contractor who was to manufacture the magazines had problems delivering them on time, and many early Bren Tens were shipped to dealers and customers without magazines. This, combined with the high price of the Bren Ten (MSRP in 1986 was US$500), caused the company to cease operations in 1986, after only three years of manufacture. Had not Colt made the rather surprising decision to bring out their Delta Elite pistol, a 10 mm Auto version of the venerable Government Model, in 1987, the cartridge might have sunk into undeserved obsolescence, an obscure footnote in firearms history.

Due to media exposure (primarily in the television series Miami Vice), demand for the Bren Ten increased after production ceased. In the five years after production ceased, prices on the standard model rose to in excess of US$1400, and original Bren magazines were selling for over US$150 (Blue Book of Gun Values, S. P. Fjestad, 13th edition, 1992).

The FBI adopted the 10 mm Auto round in the late 1980s along with the S&W model 1076 (a short barreled version of the 1026 with a frame-mounted decocker). The story goes that agents began having difficulty handling full-power 10 mm loads. The FBI then submitted a requirement for a reduced-recoil loading. This later became known as the "10 Lite", or "10 mm FBI" load. Pistol reliability problems increased with this lighter load and Smith and Wesson saw this as an invitation to create something new: a shortened version of the 10 mm. This new round was called the .40 Smith and Wesson. The .40 S&W would function in a 9 mm Luger-sized pistol; the advantage was that smaller-handed shooters could now have a 9 mm-sized gun with near-10 mm performance. The .40 S&W has become the most popular handgun caliber among law enforcement agencies in the US, while the 10 mm Auto has all but disappeared outside the hands of the hobbyist. Glock is one of the few manufacturers that still offer handguns in 10 mm. Other manufacturers include makers of 1911 style pistols (Kimber and Dan Wesson both produce models) and the Italian company Tanfoglio (marketed in the US by EAA).

Still, 10 mm loyalists are likely to denigrate the .40 S&W as ".40 Short and Weak".^[1]^[2] This is a bit of an overstatement, as the .40 S&W can come very close to 10mm performance in lighter bullet weights. Only in heavier weight loads does the 10mm pull dramatically ahead, probably due to the larger case capacity.

Since its introduction, the 10 mm Auto has had a reputation for accuracy which the shorter cartridge seems unable to match. Recently, it has had a small resurgence in popularity, but ammunition can still be more expensive and harder to find than the common .40 S&W. Most avid 10 mm shooters today are handloading due to the price of factory-loaded ammunition which may go as high as US$37 for 25 rounds. Companies such as DoubleTap Ammunition have begun offering full power 10 mm Auto loads in "common" price ranges.

[edit] Performance

The 10 mm Auto falls between the .357 magnum and the .41 Magnum in muzzle energy for popular loadings. For example, some commercial loadings are as follows: .357 Mag: 584 ft·lbf for 125 gr @ 1450 ft/s; 10 mm: 744 ft·lbf for 165 gr @ 1425 ft[1]; .41 Mag: 788 ft·lbf for 210 gr @ 1300 ft/s. The 10 mm load given is about maximum for SAAMI established pressure levels, while the .357 and especially the .41 Magnums are commonly handloaded to significantly higher levels than these samples. Top .357 Magnum loads will equal top 10mm loads from similar barrel lengths. Recoil energy of full-power loads is also comparable, being 9.4, 11.2, and 15.6 ft·lbf respectively for these loads (computed using the same powder and weight of gun). The 10 mm Auto may be used for deer or other medium game at short range. Ted Nugent is known for using a Glock 20 with an extended barrel when hunting wild boar.

Most 10 mm handguns are not designed for long range shooting often desired in hunting; a few revolvers (using half-moon clips to adapt the cartridge) are made in this chambering, and offer another choice for hunters. Much currently manufactured 10 mm ammunition is closer in performance to the "FBI load" than the full power 10 mm; these still offer sufficient power for defense applications, yet their recoil is more comparable to the .45 ACP in similar guns. A few smaller companies offer full-power ammunition for this chambering. Due to the less common availability and higher than average cost of commercial ammunition, it is more a handloader's cartridge than most other popular auto pistol rounds. It's not difficult to find 10mm commercial ammo in a well stocked shooting store, but it is more difficult to find than .40SW and 9mm in "box stores" and the like.

The 10 mm Auto cartridge operates at very high pressure in comparison to other defensive pistol cartridges, such as the .38 Special or the .45 ACP. Its maximum average pressure of 36,000psi is closely comparable to that of the .357 Magnum or the .44 Magnum, allowing it to develop true "magnum" velocities. Original loading was a 200 grain (13 g) bullet at 1200 ft/s (366 m/s), yielding 635 ft·lbf (861J) of kinetic energy at the muzzle. Today, Cor-Bon/Glaser lists a 180 gr "Hunter" loading of 1320 ft/s and 696 ft·lbf (943 J). This is nearly twice the energy of a .45 ACP. Double Tap Ammunition offers a 135 gr loading at 1600 ft/s producing an astonishing 767 ft·lbf (1040 J) of energy, up to "10mm 230gr. WFNGC Hardcast" with Ballistics: 1120fps/ 641 ft./lbs for heaviest and deepest penetrating 10mm in existence. Such a wide range of bullet weights at magnum velocities demonstrate the 10mm's versatility. The 10mm is able to match or exceed both .357 Magnum and .45 ACP performance for given bullet weights, all in a 1911 or similar form factor.

[edit] Usage

The 10 mm Auto is suitable for hunting medium-sized game at moderate ranges and is certainly more than adequate for defensive or tactical use; and one of the few true semiautomatic, rimless cartridges that is legal for hunting whitetail deer in many states.

Today, the 10 mm Auto cartridge is generally used to fend off medium-sized dangerous animals, as a high-powered defensive handgun, and for hunting, especially by those who prefer the flatter carry profile and higher cartridge capacity of an automatic pistol versus a magnum revolver. It is used as a personal defense cartridge. It is also an inherently accurate chambering, and one that makes major in IPSC even in lighter loadings.

Despite the FBI switching to the .40 S&W, there are still a number of law enforcement agencies that issue the 10 mm including the Albuquerque N.M.P.D. , the Anniston, Alabama P.D., Billings Montana P.D., and the Winnipeg Municipal Police Department.

The 10 mm's relatively flat trajectory has been regarded by some as moot in self-defense situations against human antagonists, given FBI statistics that indicate the average self-defense shooting takes place at 7 yards (21 feet) or less, and shooting a perceived threat at greater distances makes legal defense quite problematic for civilians.

[edit] Synonyms

10 mm Auto
10 mm Automatic
10 mm Norma
10 mm FBI
The Centimeter (this name is also used to refer to a wildcat cartridge based on the 10mm Auto, which is trademarked by Pistol Dynamics[2])