Tisas Arms PX-5.7 5.7x28mm 20+1 4.70" Black QPQ Carbon Steel Optic Ready/Serrated Slide, Black Polymer Frame w/Picatinny Rail, Polymer Grip

The 5.7X28mm was introduced by FN in 1993, developed for a new concept called Personal Defense Weapon (PDW), intended to replace the pistol, submachinegun, and carbine for miliitary use. The concept is a compact, selective fire weapon intended for use within 200 meters, firing a light projectile for controllable recoil. The 5.7X28mm was designed for FN's P90 PDW. It uses a short bottlenecked case firing a 31-grain .224-inch bullet at 2325 fps. Performance exceeds military handgun cartridge, especially as range increases. Although many experts find the concept sound acceptance by the military has not been rapid. — Craig Boddington