The AKS-74U (U—Ukorochenniy), which in terms of tactical deployment, bridges the gap between a submachine gun and an assault rifle. It is intended for use mainly with special forces, airborne infantry, rear-echelon support units and armored vehicle crews. The rifle's compact dimensions, compared to the AKS-74, were achieved by using a short 210 mm (8.3 in) barrel (this forced designers to simultaneously reduce the gas piston operating rod to an appropriate length). In order to effectively stabilize projectiles, the barrel’s twist rate was increased from 200 mm (1:8 in) to 160 mm (1:6.3 in). A new gas block was installed at the muzzle end of the barrel with a new conical flash hider combined with a cylindrical muzzle booster, which features an internal expansion chamber that increases the weapon's reliability. The booster enhances the recoil impulse by supplying the gas system with residual gases from the barrel. The chrome-lined muzzle booster also burns any remaining propellant thus reducing the gun's signature. The muzzle device locks into the gas block with a spring-loaded detent and features two notches cut into the flash hider cone, used for disassembly using the supplied cleaning rod. The forward sling loop was relocated to the left side of the carbine and the front sight was integrated into the gas block.