180mm ‘Crazy Jet’ Inner Barrel for GBB Replicas (6.02mm – Tightbore) MAPLE LEAF GBB Inner Barrels have been designed to improve the performance of your Gas-Blow-Back (GBB) Airsoft Replica. Many OEM Airsoft Replicas feature lower-tolerance Inner Barrels with inner diameters as high as 6.08 or 6.10mm. By installing an Inner Barrel with a reduced inner diameter, less air can escape around the edge of the BB whilst traveling down the inner barrel. This escaping air can destabilize the flight of your BB, so a tighter inner barrel results in improved flight. MAPLE LEAFs ‘Crazy Jet’ Inner Barrels are not only a tighter bore than many standard Inner Barrels, but they have also utilized the escaping air to improve the trajectory of in-flight BBs. After the BB has traveled down the ‘Crazy Jet’ inner barrel for a short time, the BB will pass a section of the Inner Barrel that features channels for the high-pressure air behind the BB to escape down. These channels control the airflow, so instead of random turbulence, the escaping air pressure creates a secondary “barrel”, or air pocket within the barrel that further controls the trajectory of the BB.