MetalMayhem
Pic of the launcher
MetalMayhem is my first attempt at a metal gun, and my first attempt at a coaxial piston valve. The launcher is a coaxial piston type, made mostly of spare parts I had already. The barrel is 3/8" copper pipe, and the chamber is part of an old aluminum bike pump. The piston is extremely simple, its only a 1" copper cap with neoprene bolted onto it. I thought this gun would be powerful, but I had no idea how fast it would actually shoot! I split a cork in two on my first shot. The cork only came into contact with some wadded up cloth. The pilot area (area being the piston) is exhausted with a 1/4" ball valve.
This Pic shows the internals of the gun. They are laid out how it would be inside the chamber. The white thing is to center the barrel. It is just a ground out and cut down 1" endcap. Sheet PVC would work also, as would wood or anything really. The back of the chamber (right end) is plugged with the original bike pump plug. It is held into place with the 1/4" pipe nipple that the exhaust ball valve is attached to.
Oh, by the way, this little guy is FAST! It amazed me for its size! I can shoot big ball bearings (fit perfect in the barrel) at 411fps, but here is the amazing shot:
Chrony data when shooting a 3/8" cork at 120psi.
Needless to say, I almost wet my pants with excitement when I saw a number that big on my chrony!
The guts...
The piston. See! I told you it was simple!
The seat end of the barrel, along with the spacer and front of the piston.
Close Up of the JBWeld Joint
Close Up of the Exhaust Valve