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The FN 5.7×28mm
is a small-caliber, high-velocity cartridge designed and manufactured by FN Herstal in Belgium. It is a bottlenecked centerfire cartridge that is somewhat similar to the .17 HMR, .22 Hornet or .22 K-Hornet. The 5.7×28mm was developed in conjunction with the FN P90 personal defense weapon (PDW) and FN Five-seven pistol, in response to NATO requests for a replacement for the 9×19mm Parabellum cartridge.

The armor-piercing cartridge is used by the United States Secret Service in the FN P90.

DescriptionEdit

In 2002 and 2003, NATO conducted a series of tests with the intention of standardizing a PDW cartridge as a replacement for the 9×19mm Parabellum cartridge. The tests compared the relative merits of the 5.7×28mm cartridge and the 4.6×30mm cartridge, which was created by Heckler & Koch as a competitor to the 5.7×28mm. The NATO group subsequently recommended the 5.7×28mm cartridge, citing superior performance in testing, but the German delegation objected and the standardization process was indefinitely halted.

By 2006, FN's 5.7×28mm firearms—the P90 personal defense weapon and Five-seven pistol—were in service with military and police forces in over 40 nations throughout the world. In the United States, 5.7×28mm firearms are currently used by numerous law enforcement agencies, including the U.S. Secret Service.

In addition to being used in the FN P90 and FN Five-seven firearms, the 5.7×28mm cartridge has subsequently been used in a number of other weapons, such as the AR-57 and FN PS90 carbines. Excel Arms has developed four firearms chambered in 5.7×28mm, and MasterPiece Arms offers three different 5.7×28mm firearms. The 5.7×28mm cartridge itself is produced in a number of varieties, two of which—the SS195LF and SS197SR—are currently offered by FN to civilian shooters for use in 5.7×28mm firearms.

The 5.7×28mm cartridge was designed by FN Herstal specifically for use in the FN P90 personal defense weapon and FN Five-seven pistol. Subsequently, it has been used in a number of other weapons, such as the FN PS90 carbine and the AR-57, an upper receiver for M16/AR-15 rifles. The ST Kinetics CPW can be configured for the 5.7×28mm cartridge by changing the barrel and magazine groups. Excel Arms has developed four firearms chambered in 5.7×28mm, and MasterPiece Arms offers three different 5.7×28mm firearms.

The 5.7×28mm cartridge weighs 6.0 g (93 grains)—roughly half as much as a typical 9×19mm Parabellum cartridge—making extra ammunition less burdensome, or allowing more ammunition to be carried for the same weight. Since the 5.7×28mm cartridge also has a relatively small diameter, an unusually high number of cartridges can be contained in a magazine. The cartridge has a loud report and produces considerable muzzle flash (when fired from a pistol), but it has roughly 30 percent less recoil than the 9×19mm cartridge, improving controllability. Due to its high velocity, the 5.7×28mm also exhibits an exceptionally flat trajectory.

One of the design intents of the SS190 variety of this cartridge was that it have the ability to penetrate Kevlar protective vests—such as the NATO CRISAT vest—that will stop conventional pistol bullets. Fired from the P90, the SS190 is capable of penetrating the CRISAT vest at a range of 200 m (219 yd), or a Level IIIA Kevlar vest at the same range. However, sporting variants of the 5.7×28mm are classified by the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) as not armor-piercing.

Photo of various cartridges, showing from left to right: 9×19mm Parabellum, .40 S&W, .45 ACP, 5.7×28mm, 5.56×45mm NATO, .300 Winchester Magnum, 2.75-inch 12 gauge, and 3-inch 12 gauge

From left to right: 9×19mm Parabellum, .40 S&W, .45 ACP, 5.7×28mm, 5.56×45mm NATO, .300 Winchester Magnum, and a 2.75-inch (70 mm) and 3-inch (76 mm) 12 gauge. According to FN, the 5.7×28mm cartridge has an effective range of 200 m (219 yd) and a maximum range of 1,800 m (1,969 yd) when fired from the P90, and an effective range of 50 m (55 yd) and a maximum range of 1,510 m (1,651 yd) when fired from the Five-seven. In testing, the SS190 and similar 5.7×28mm projectiles consistently turn base over point ("tumble") as they pass through ballistic gelatin and other media, using the 21.6-mm (.85 in) projectile length to create a larger wound cavity. However, some are skeptical of the bullet's terminal performance, and it is a subject of debate among civilian shooters in the United States.

The 5.7×28mm projectile potentially poses less risk of collateral damage than conventional pistol bullets, because the projectile design limits overpenetration, as well as risk of ricochet. The lightweight projectile also poses less risk of collateral damage in the event of a miss, because it loses much of its kinetic energy after traveling only 400 m (437 yd), whereas a conventional pistol bullet such as the 9×19mm retains significant energy beyond 800 m (875 yd). This range exceeds the engagement distances expected for the 5.7×28mm cartridge's intended applications, so the cartridge's limited energy at long range is not conversely considered to be disadvantageous.

Since the 5.7×28mm SS190 projectile does not rely on fragmentation or the expansion of a hollow-point bullet, the cartridge (and 5.7×28mm firearms) are considered suitable for military use under the Hague Convention of 1899, which prohibits the use of expanding bullets in warfare.

FN's 5.7×28mm cartridge cases are covered with a special polymer coating for easier extraction with the PS90 carbine due to the high chamber pressures and lack of case tapering. In addition, this coating ensures proper feeding and function in the magazines.