Armorer Works AW 6.01mm 74mm Triad Tightbore Inner Barrel with Silicone Hop Up Performance Bucking For Hi-Capa Series GBB Pistols AirsoftArmorer Works AW 6. 01mm 74mm Triad Tightbore Inner Barrel with Silicone Hop Up Performance Bucking. Made out of Electroplated Brass and Silicone. High Performance Bucking. Fluted grooves on muzzle end of inner barrel for reduced turbulence, enhanced trajectory stability and reduced friction when projectile exits the inner barrel . Includes high performance silicone bucking with specialized integrated nub. Suitable for most standard length Tokyo Marui