It's time for the big one... help me out

[Boomer_]

DO NOT use a cleanout cap, they are dangerous i tried it and they can break and stuff and not good things, use reducers 'til you get it down to 1 or 3/4" then plug 3/4 inch pipe with a male end on it and a modded sprinkler valve. also on mine i have a 3" bushing with the round lip cut off (use the lip part) for a barrel support, then i used a rubber pipe connector on the barrel (piston side) to make a seal on the piston. also, 3' sch 40 fittings fit inside 4" pipe, so i used a 3" cap as a piston. I might be able to get pictures of it for you. also dont screw the piston up, sand off the lettering thats embossed in it and thats it. make sure to put a piece of air hose or some kind of shock absorbing kind of thing in behind the piston. the force of the piston is a good amount. gl.