I did not plug the pump for legality reasons, only internals mods performed were reinforcing the trigger and putting a cut SCH40 Conduit on the air tank. I put an ls scope on the gun for looks.
You will need:
5/8" brass (depending on barrel material used this may change)
I took the 5/8" brass and cut a slot into it for taking in stefans from an LS clip. Etape was also put on the innter lip of the breech in order to retain a better seal. I used 12" of Petg as the barrel because of it's looser fit which is ideal for air guns.
To attach the brass to the conduit on the airtank, I stuck the brass into to a piece of SCH40 (The insides were dremeled to fit) and glued it in. The SCH40 then fits into the conduit allowing for me to remove it if necessary.
The bolt is made by nailing a piece cpvc pipe to the tee. At the end of the cpvc I took a large screw I had lying around and placed it on the end of the pipe. This acts as the handle of the bolt. However, the bolt was still rather flimsy at this point. I took random pieces of cpvc and glued them in on the inside to help guide the bolt smoothly.
Using a dremel, I cut holes on both sides of the shell, one for the clip to fit in, and one for the bolt to slide from. The clip simply snaps around the brass and a stefan is loaded when the Petg moves forward and back. Ignore the hole in the shell.
To prime, push bolt forward and pull back. Then pump the gun and fire. Ranges have not been measured but I was able to shoot through cardboard from 50 feet away.
Edit: Pictures have been updated and an image of the full assembly has been added.
Edited by Phibonnachee, 10 June 2009 - 09:23 PM.