my own experience of opening the ports on HW's springers is if they are opened more than 3.5 mm they shoot cr@p with very sharp harsh recoil' 3.5 mm is spot on though but gas pressure or spring pressure will need to be reduced to keep it legal if port is opened to say 4mm i've found its the opposite' spring or gas pressure needs to be increased just to get it near the legal limmit' thus the higher recoil & harshness.Originally Posted by manxteddy
Dave.