1 x BC01781 senco part number BC0178 Top piston bumper on the SN325 Framing nailers 3 x senco BC01783 top piston bumpers # BC0178 Circled in REDAvailable Qty: 18 Used in the Senco SN-325 and SN-325+ models, stops the piston when it retracts back to the firing position. Post navigation Senco LB3499 on ebay SN325 Rebuild kits