This polycarbonate piston from Guarder is an excellent replacement for a lower-quality plastic piston included with some guns. The final gear (which suffers the most load when firing) is made from steel, and has been heat treated to enhance the durability of this critical piece. This piston weighs 14 grams.
This is a full tooth piston, and is compatible with standard straight-cut gears. This piston is not compatible with helical-cut gears, as the profile of helical-cut sector gears is incompatible with the full-tooth design of this piston.