After doing the standard mods, I drilled a hole into the piston where I wanted to add a PVC extension (see other pictures for where I added it). I don't know what drill bit size I used, but it works good for 1/4" threaded brass fittings. That second hole inside the piston was already there, not from my drilling.
Two 1/2" PVC end caps, a 1/4" brass pipe nipple, and a little bit of 1/2" PVC. This is what the extension is made of. Build it as large as you dare (I made it as small as I could) with some pvc cement; Drill a hole into the side (same size as the hole in the piston).
Screw the nipple into the PVC extension and then screw the extension into the piston. Goop the hell out of it so it doesn't leak, and then hot glue, or other glue of choice, to reinforce it. Cut the top of the shell so that the extension can fit and so that it can move with the piston. Cut the front of the shell off so that that longer barrels will fit. Make a PETG clip with long barrels on it. I used 6" barrels because that was easiest.
I got 60-85' flat with one clip.
Ranges were varied because some of the barrels on the PETG clip were leaky as hell. The piston needs more banding and making a brassed clip would probably yield better ranges also. Have fun out ranging most guns at rapid fire.
Edited by oodalumps, 18 July 2008 - 02:11 PM.