5.7x28mm
In the 1980s, lightweight personal body armor was becoming more prevalent among Soviet units. While these flak jackets were easily penetrated by rifle fire, they were able to defeat 9x19mm ball rounds. So there was growing concern over NATO?s 9x19mm weapons being rendered obsolete. Fabrique Nationale recognized this threat and began working on a solution in the 1980s, an effort that picked up steam when NATO established the CRISAT target--a 1.6mm titanium plate and 20 Kevlar folds--as a penetration standard. FN responded with a small-caliber, high-velocity cartridge called the 5.7x28mm.
A small bottlenecked cartridge with a 28mm-long case, it?s topped with a .224-inch-diameter projectile. The standard military SS190 ball loading features a 31-grain armor-piercing FMJ-BT projectile, and there are tracer, subsonic and practice rounds, too--as well as commercial 40-grain sporting ammunition (SS196 and SS197). (Editor?s note: FN and ATK, parent of Federal Cartridge, recently signed a distribution agreement under which ATK would become the exclusive distributor of commercial sporting ammo in the U.S.; the restricted law enforcement and military ammunition remains an FNH USA product.)
The cartridge?s overall length is 40.5mm, and it weighs half what a 9x19mm cartridge does. To cut through soft body armor, the .224-diameter SS190 projectile incorporates a cone-shaped steel penetrator sitting atop an aluminum core surrounded by a steel jacket.
Velocity of the 5.7x28mm SS190 ball load from a P90 PDW?s 10.2-inch barrel is 2,346 fps. Fired from an FN Five-seveN service pistol it still clocks a respectable 2,133 fps. Despite the high muzzle velocity, recoil is approximately 30 percent less than a 9x19mm. The 5.7x28mm is capable of defeating the CRISAT target at 200 meters.