The AW Custom 6.01mm Tightbore Inner Barrel + Performance Bucking 74mm length is in stock at Crown Airsoft. Made of Electroplated Brass and Silicone, it is compatible with most WE Airsoft Gen 2 and AW Custom Hi-Capa GBB Pistols. This has a high pperformance bucking and rifled grooves at the muzzle end for reduced turbulence, enhanced trajectory stability and reduced friction when the BB exits the inner barrel.