pneumatics for featherweight

[Liftoff]

50gr cartridge is quite small, the volume of that cartridge is around 0.04lt. Your cylinder has 0.39lt so the buffer you need should ideally be around 1lt, but a 12oz paintball bottle will do.
You can use a double acting cylinder with the QEV, connect it to the bottom port, use a 5/2way valve to fire the ram. To re-cock the ram use a bungee.

[maddox10]

For a buffertank you should look for a reservoir at least 3 times the volume of the ram.