Why do you change the oil? When I used fartguns I didn't touch them unless something was wrong.
This gun is still under my development plan. It has a ported inner barrel and modified trigger assembly.
I traded out the stock piston for a later model and will be examining the OEM piston in a scope as I did all the stressed parts. I plan on pushing this kited gun to high pressures until the piston fails. Then it will see some Ti bits I'm making.
Cheers, Don