This CNC machined piston head is designed to replace the standard cup-seal in KSC/KWA G-Series, KWA M-Series and ATP series GBBs. A high quality O-ring on a precisely machined aluminium body is used to provide a better seal than worn or degraded cup-seals which can result in increased gas efficiency.

Each piston head is machined from 6026 T9 aluminium to a tight tolerance and includes 2 spare O-rings (3 in total) ready for future replacement.

In order to install this piston head the brass pin which the cup-seal piston head fits onto must be removed from the BBU (blow back unit), this part is pressed in and can normally be pulled out or levered out using long nose pliers, once removed the new piston head is pressed into the BBU, a small amount of silicone oil or grease should be applied to the O-ring before installation.

Designed & manufactured in the United Kingdom by Lees Precision Engineering.