FN 5.7×28mm

The FN 5.7×28mm is a small-caliber, high-velocity, smokeless powder, rebated rim, bottlenecked, centerfire handgun and rifle cartridge designed and manufactured by FN Herstal in Belgium. It is similar in length to the .22 WMR and to some degree similar also to .22 Hornet or .22 K-Hornet.Wikipedia
Bullet diameter5.70 mm (0.224 in)
Rifling twist228.6 mm (1 in 9 inch)
Used by40+ nations; see:: P90 Users; Five-seven Users
Case length28.90 mm (1.138 in)
Case capacity0.90 cm3 (13.9 gr H2O)
Maximum pressure440.00 MPa (63,817 psi)
Overall length40.50 mm (1.594 in)