Madbull M140 Spring
Upgrade your AEG's fps to 450 to 470fps. It is highly recommended to upgrade plastic bushings and spring guide to metal bushings and spring guide with this product. Also, it would be wise to upgrade plastic pistons to polycarbonate piston; plastic piston heads to duracon piston heads; and standard gears to reinforced steel gears. Finally, just to be safe, upgrade the standard gearbox shell to a reinforced gearbox shell. Finally for best results a battery upgrade is also recommended