COWCOW Reinforced Piston Head, TM G19/G17 Gen4/M&P9

The COWCOW Reinforced Piston Head is a drop-in piston head for the original blowback unit (BBU) in the Tokyo Marui G19 Gen3 and Gen4, G17 Gen4, V10, M&P9 and M&P9 V-Custom. It replaces the original piston head in the blowback unit without modification and is made to seal better and withstand harder impacts.

The piston head sits at the rear of the nozzle unit and is the part the gas pushes against when the slide is driven back. It therefore directly affects how strong and consistent the blowback is. The original piston head can leak or deform over time – especially if the pistol has been upgraded with stronger springs – and then gas is lost and recoil becomes weak or irregular.

Features of the piston head

Advantages over the original piston head:

• Better air seal: Designed to seal better than the original, so less gas is lost in the blowback cycle.
• Withstands high impact pressure: Built for the high pressures and impacts that occur with every shot – also with upgraded springs.
• Consistent performance: A tight, dimensionally stable piston face gives more consistent recoil and cycling from shot to shot.
• Longer life: According to COWCOW, more wear-resistant than Tokyo Marui's original piston head.
• Drop-in for several Marui models: Fits the original BBU in the TM G19 Gen3/Gen4, G17 Gen4, V10, M&P9 and M&P9 V-Custom – not the G17 Gen5, which has its own version.

Maintenance and safety

• De-gas and remove the magazine before taking off the slide and disassembling the nozzle unit.
• Lightly lubricate the piston head with silicone oil when fitting, so it slides freely and seals optimally.
• Check the nozzle and valve for wear at the same time – a new piston head won't help if there are leaks elsewhere.
• Our workshop in Aulum, Denmark can replace the piston head as part of a service.