The air shaft introducing foreign advanced production equipmentand fabrication technology, using imported balloon, the shaft is casting byaluminum alloy, shaft body plating chromium, accurate assembly, convenient touse and long operate life. When used with my companys professional configurationof the air gun mouth filling gas, to make the shaft of off-axle apperanceuniform expansion, thereby lock nitrogen-treated barrel, when unloading, presson deflated mouth to deflated, then nitrogen-treated barrel can be unloaded.