Itís powered by air pressure and is pumped up by 2 bicycle frame pumps mounted on the body with a tandem handle, making it doubly efficient. The primary chamber is 2-inch SCH40 PVC with ľ inch threads coming out of both end caps. On the back are the two Schrader valves, which are called snifter valves (home hardware) and are connected with a ľ inch brass tee to the chamber and a pressure gauge measuring the initial pressure. The threading through the end cap is reinforced internally with a rubber washer, metal washer, and length of Ĺ inch copper, which is sleeved onto the threaded ľ inch steel pipe and is secured by a nut. As a precaution I poured a generous amount of epoxy into the end cap, sealing the washers and the seam between the steel washer and the copper pipe.
On the other side of the 14-inch pressure vessel is another steel threaded end cap that is connected to a ľ inch pressure regulator that lowers the pressure to a much more usable pressure. From a 90-degree brass fitting goes to a male copper adapter that threads into an electronically actuated sprinkler valve. The valve controls the flow of air into the secondary (firing) chamber which is roughly 7 inches long made of 1-1/2 SCH40 PVC and has a 90 degree bend to utilise as little space as possible. The firing chamber is threaded onto a brass ľ inch tee that connects to a second sprinkler valve that empties the firing chamber. Connected to the sprinkler valve is the bolt. The boltís movement is a little tricky to explain as it moves only an inch or so forward and back and rotates 180 degrees. The main idea for this is to have a somewhat gravity fed where the cartridge falls into the bolt from a rotary linear magazine (not connected to the gun but built) which holds 24 shells. The cartridge sits in the bolt that is then rotated 90 degrees and pushed forward to seal the faces of the shell. The shell is made of Ĺ inch copper with 2 copper couplers with a 1/8-inch recess on each side to allow for the shells to sleeve into ĺ inch aluminium tubing and provide a great seal and also allow enough play for the shells to fall into the handle, falling out the front of the handle. I can use CPVC shells with 2 copper couplers, which is lighter but the 5/8 inch FBR I have fits beautifully into Ĺ copper and loose fitting in ĺ inch aluminium. If I want to use micro Stefans I have CPVC and Ĺ FBR just in case. The barrel is fixed to the gun and is about 16 inches long, with a gator lock on the end. I made a silencer that adds another effective 10 inches to the barrel and does great to help muffle the massive thunk the gun makes.
There is so much I may have missed and left out, this is mainly just a rough description of my homemade. Iím just happy the fucker is finally built. I put the electrical wiring in tonight and have only test fired it a few times, but the velocity and power behind it is intense. Iíve left the air assembly as one working piece, and the barrel assembly another. Iím planning on making a paintball loser assembly and a large bore foam chucker that uses Ĺ inch foam pipe insulator and brass plumbing ma-jiggers (I forget the name) for shells. I will be using the plastic alternative shells that fit 3 pieces of Ĺ inch copper real well to make a shotgun round.
My fiancť is especially glad it's finished, she feels neglected when I spend so much time in her basement (I use her basement as my workshop).
So I'll get pics tomorrow afternoon.
Edited by FromAbove, 25 April 2006 - 08:54 PM.