FN 5.7×28mm

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.^[11] 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 and AR-15 rifles.^[17][18] The ST Kinetics CPW can be configured for the 5.7×28mm cartridge by changing the barrel and magazine groups.^[43] Excel Arms has developed four firearms chambered in 5.7×28mm,^[19] and MasterPiece Arms offers three different 5.7×28mm firearms.^[20]

The 5.7×28mm cartridge weighs 6.0 grams (93 grains) — roughly two-thirds 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.^[44][45][46] Since the 5.7×28mm cartridge also has a relatively small diameter, a relatively high number of cartridges can be contained in a magazine.^[47] The cartridge has a loud report and produces considerable muzzle flash (when fired from a pistol),^[48] but it has roughly 30 percent less recoil than the 9×19mm cartridge, improving controllability.^[33][46][49] Due to its high velocity, the 5.7×28mm also exhibits an exceptionally flat trajectory.^[46][50]

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.^[33] 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.^[32][33] 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.^[36]

According to FN, the 5.7×28mm cartridge has an effective range of 200 m (220 yd) and a maximum range of 1,800 m (2,000 yd) when fired from the P90,^[38] and an effective range of 50 m (55 yd) and a maximum range of 1,510 m (1,650 yd) when fired from the Five-seven.^[35] 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 (0.85 in) projectile length^[35] to create a larger wound cavity.^{[11][45][51][52]} However, some are skeptical of the bullet's terminal performance, and it is a subject of debate among civilian shooters in the United States.^[52]

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.^[51][53][54] 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 (440 yd), whereas a conventional pistol bullet such as the 9×19mm retains significant energy beyond 800 m (870 yd).^[50] 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.^[50]

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.^[52]

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.^[45] In addition, this coating ensures proper feeding and function in the magazines.^[45]

The 5.7×28mm has a cartridge case capacity of 0.90 ml (13.85 grains H₂O).^[48]

Americans define the shoulder angle at alpha/2 ≈ 35 degrees. The common rifling twist rate for this cartridge is 1:228.6 mm (1:9 in), 8 grooves, Ø lands = 5.53 mm, Ø grooves = 5.62 mm, land width = 1.63 mm and the recommended primer type is small rifle.^[7]

According to the official C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) rulings, the 5.7×28mm can handle up to 3,450 bar (345 MPa; 50,038 psi) Pmax (the nominal maximum) piezo^{[clarification needed]} pressure. In C.I.P. regulated countries, every rifle cartridge combination has to be proofed at 125% of this maximum C.I.P. pressure to be certified for sale to consumers, referred to as "PE". This means that 5.7×28mm chambered arms in C.I.P. regulated countries are currently (2018) proof tested at 4,313 bar (431 MPa; 62,555 psi) PE piezo pressure.^[7] Despite the relatively high maximum pressure, the bolt thrust of the 5.7×28mm is on a similar level when compared with traditional service sidearm cartridges.

Fired from the longer 40.74 cm (16.04 in) barrel of the PS90, the muzzle velocity of SS195LF is roughly 60 m/s (200 ft/s) faster, and the muzzle velocity of SS197SR is roughly 45 m/s (150 ft/s) faster.^[55] Fired from the shorter 12.2 cm (4.8 in) barrel of the Five-seven pistol, the muzzle velocity of SS195LF is roughly 90 m/s (300 ft/s) slower, and the muzzle velocity of SS197SR is roughly 60 m/s (200 ft/s) slower.^[55][56][57]

SS90 prototype

The SS90 was an early prototype round used only in the earliest examples of the P90. It used a lightweight 1.5-g (23 grain) full metal jacket bullet with a polymer core, which it propelled at a muzzle velocity of roughly 850 m/s (2,800 ft/s). The SS90 was abandoned in 1994 in favor of the heavier and shorter 2.7 mm (0.11 in) SS190 projectile.^[28]

SS190 duty

The SS190 FMJ, a refinement of the SS90, was introduced in 1993.^[6] It offered superior performance over the prototype projectile as well as slightly reduced length.^[6] The latter change allowed it to be used more conveniently in the Five-seven pistol, also being developed at that time.^[28] Fired from the P90, the SS190 propels a 2.0-g (31 grain) bullet at a muzzle velocity of roughly 715 m/s (2,350 ft/s). It has a steel penetrator and an aluminum core.^[55] The SS190 has been manufactured with a plain, black, and a black-on-white tip color.^[17][58][59] It is classified by the ATF as armor-piercing (AP) handgun ammunition, and its sale is currently restricted by FN to military and law enforcement customers.^[17][36]

In testing done by Houston Police Department SWAT, the SS190 fired from the P90 into bare ballistic gelatin exhibited penetration depths ranging from 28 to 34 cm (11 to 13.5 in).^[32] In testing in 1999 by the Royal Canadian Mounted Police (RCMP), the SS190 fired from the P90 at a distance of 25 m (27 yd) exhibited an average penetration depth of 25 cm (9.8 in) in ballistic gelatin after passing through a Level II Kevlar vest.^[53]

L191 tracer

The L191 (also formerly called the SS191)^[60] is a tracer cartridge designed for easier bullet spotting in dim light.^[17] Combustible chemicals packed in the rear of the L191 projectile create a light trail visible up to 200 m (220 yd).^[59] The L191 has been manufactured with red and red-on-black tips.^[17][58] The performance and trajectory of the L191 is identical to the SS190.^[44][46] For this reason, it is also classified by the ATF as armor-piercing handgun ammunition, and its sale is currently restricted by FN to military and law enforcement customers.^[17][36]

SS192 hollow-point

The SS192 was discontinued in late 2004.^[60] It used a 1.8 g (28 grain) hollow point bullet with a copper jacket and an aluminum core.^[35] The projectile had a length of 21.6 mm (0.85 in).^[35] It had an unmarked hollow nose with a depth of 7.6 mm (0.30 in) and a 0.8 mm (0.031 in) opening.^[35] The SS192 was classified by the ATF as not armor-piercing, and in testing by FNH USA it did not penetrate a Level IIIA vest when fired from the Five-seven.^[36]

SB193 subsonic

The SB193 (also formerly called the SS193)^[60] is a subsonic cartridge featuring a 3.6-g (55 grain) Sierra Game King FMJBT (FMJ boat tail) projectile. The SB193's sub-sonic speed eliminates the distinctive "crack" created by supersonic rounds. The muzzle report is also reduced when using the sub-sonic ammunition together with a suppressor. Due to the greatly decreased muzzle velocity, the SB193 benefits from a slightly reduced recoil force of 1.3 kgm/s.^[61] The SB193 can be identified by its white tip color.^[17] Its sale is currently restricted by FN to military and law enforcement customers.^[17]

T194 training

The T194 training round was discontinued in 2002. It could be considered an early version of the SS192 or SS195. It used the same 1.8-g (28 grain) copper-jacketed aluminum core bullet, propelled at the same muzzle velocity.^[44] It had a green tip.^[44]

SS195LF (lead free)

The SS195LF is a commercially available cartridge that features a lead-free primer and produces ballistics similar to the SS192 round, which it replaced in late 2004.^[60] It uses the same 1.8-g (28 grain) copper-jacketed aluminum core bullet as the SS192, and it can be identified by the unmarked, hollow void at the tip and the silver-colored primer.^[17] The SS195 is classified by the ATF as not armor-piercing, and it is currently manufactured by FN Herstal in Belgium.^[10][36]

SS196SR (sporting round)

The SS196SR was introduced in 2005 and it is now discontinued in favor of the SS197SR cartridge.^[37] It featured a lead core 2.6-g (40 grain) Hornady V-Max bullet which it propelled at a muzzle velocity of roughly 500 m/s (1,600 ft/s) when fired from the Five-seven.^[37] The polycarbonate tip used in the V-Max bullet acted as a wedge, enhancing expansion of the bullet. The SS196 was classified by the ATF as not armor-piercing, and in testing by FNH USA it did not penetrate a Level II vest when fired from the Five-seven.^[36] The SS196 could be identified by its red polymer tip.^[60]

SS197SR (sporting round)

The SS197SR is currently offered to civilian shooters in addition to the SS195LF.^[17] It uses the same lead core 2.6-g (40 grain) Hornady V-Max projectile as the SS196SR,^[10] but it is loaded for a muzzle velocity roughly 30 m/s (98 ft/s) higher. The projectile has a blue-colored polymer tip instead of the red color used in the SS196 projectile tip.^[17] The SS197 has been manufactured by Fiocchi, under contract for FN Herstal, since 2006^[10][62][63] and it is distributed in the United States by Federal Cartridge Company.^[17]

SS198LF (lead free)

The SS198LF uses the same lead-free projectile and primer as the SS195LF,^[58] but propels it at roughly a 30 m/s (98 ft/s) higher muzzle velocity. It’s manufactured in Belgium. It has a green painted tip, and its sale is currently restricted by FN to military and law enforcement customers,^[17] but is widely available through retailers to civilian customers.^{[citation needed]}

American Eagle (AE5728A) TMJ

Since 2012, Federal Cartridge Company markets a loading produced by Fiocchi using a 5.7×28mm round under their American Eagle brand.^[20] Designated the AE5728A, this cartridge uses a 40-grain total metal jacket (TMJ) projectile, that is atypical in that it does not use a copper-plated bullet. The AE5728A casings are of FN manufacture, and the muzzle velocity is slightly lower than that of the SS197SR.^[64]

Non-FN ammunition

Elite Ammunition manufactures a wide variety of loaded 5.7×28mm ammunition offerings, including the "T6B" and "S4M" cartridges.^[65]

Handloading

Handloading is possible with 5.7×28mm ammunition, and 5.7 mm (0.22 in) bullets are widely available due to use in .223 Remington and 5.56×45mm NATO cartridges.^[10] Handloaders have noted that the 5.7×28mm cartridge is very sensitive to small changes in powder charge or overall length (OAL) with a bullet inserted.^[48] Bullets weighing 2.6 g (40 grains) or less are recommended for optimal use in 5.7×28mm applications,^[48] but the 228.6 mm (1:9 in) rifling twist rate (distance the bullet must travel to complete one full revolution) used in the firearms' barrels will stabilize bullets weighing up to 4.5 g (70 grains).^[10]