Action SL-MK4 220mm Barrel Kit Set will allow you to change the inner and outer barrel of the older version of the SL-MK4. A longer inner barrel will allow for more power to be pushed out increasing the fps by 15%.
Action SL-MK4 220mm Barrel Kit Set will allow you to change the inner and outer barrel of the older version of the SL-MK4. A longer inner barrel will allow for more power to be pushed out increasing the fps by 15%.