Silverback Variable Mass Piston For SRS-A1
OptimusPrime
05 Nov 2018
Video from Silverback Airsoft showing how to assemble and fine tune your Variable Mass piston for Silverback SRS-A1 pull bolt... "Available at authorised dealers, the Silverback SRS Variable Mass Piston - Pull bolt will enable you to customise your piston weight from the standard piston."