For: Prometheus Hard PistonProduct Information:
This piston recently was in two compression jams with an M130 due to a hop-up bucking refusing to let the BB pass. I heard the gear teeth make contact... in a bad way... with the piston teeth, and thought that I had at least several stripped piston teeth.
I opened up the gearbox, lo and behold there was only slight damage to one tooth. This piston must have turned God mode on at the last second.
For some reason though, this same piston did not hold up well in a KWA M4 (~390 FPS @22 RPS). It showed wear on 5 teeth after only ~3000 rounds. I'm guessing that since the KWA piston/gearbox are around .75mm to 1mm wider than a standard gearbox/piston, so the Prometheus piston was doing some moving around, and that contributed to the wear.
I have been running this piston with an M130 in a set-up capable of 20 RPS at 430 FPS, and the only damage it has seen has been from a compression jam, and it survived that with barely any damage.
-Relatively cheap. Most pistons capable of taking the stress this piston does cost ~$50.00. You can find this piston for as cheap as $32.00 in the states.