Description BSA/Gamo Piston Seal BSA / GAMO Piston Seal / Washer. Parachute style washer that was adopted by BSA / GAMO as a common piston seal component that was interchangeable between models. If your rifle is low in power, it could be because air is escaping past the piston seal from the compression chamber. These are direct manufacturer replacements for the factory-fitted piston seal. 26mm Outer Diameter 13mm Inner Diameter 5.4mm Thickness BSA MPN 16-5657 Same Design as GAMO MPN 12540 Suitable for the BSA Meteor, MK5, MK6, MK7, Comet and Polaris Air Rifles, as well as all GAMO spring and gas piston Air Rifles. Good quality piston seal for BSA/Gamo airguns of diameter 26 mm. Opened type seal is better for using with gas pistons also. Made of polyurethane.
