The gun sitting on my ping-pong table. Its about 7 feet long so getting the whole thing in the shot was a headache
The pilot/fill area with blowgun pilot and quick-disconnect
The QEV and union loading
The regulator gauges. There's a lot more room for higher pressures if I have the nerve.
The gun has a 1/2" copper barrel and 1" copper chamber. The barrel is 66" long and has a volume of 13 in^3, and the chamber is 75" long and has a volume of 59 in^3, for a C:B ratio of about 4.5:1. Since I have plenty of available gas filling capacity I decided to go for broke on the C:B ratio to maximize power. I used a McMaster 3/4" QEV and a blowgun pilot valve.
The ammo I used was a steel-tipped dart made of steel, wood, and (as always) duct tape. The center of mass is slightly forward of the midpoint, and the duct tape wrapping allows it to fit snugly in the barrel and places the center of pressure at the rear. The dart always strikes tip first. The photo is of a 3/4" dart and this gun used a 1/2" dart, but its the same except for the thickness of the duct tape tail.
And now for some damage pics (all from one shot):
The target before the shot (actually reassembled afterwards, but you get the idea). It is two halves of a model tank I made when I was little placed back to back.
After the shot. The front half was completely split in half and flew apart. The back half mostly survived.
A bit blurry, but shows that the wood is slightly over 3/4" thick.
The steel tip of the dart fully penetrated the second layer as well, but did not shatter it in the same way as the first layer. The dart completely disintegrated, all I could find was a splintered section of the wooden middle bit.
I would include GGDT data but I don't know how to model a QEV.
I plan to up the pressure if I can convince myself the gun isn't gonna disintegrate.
an alternative gas to the rather heavy CO<sub>2</sub> would bring about better performance for the same pressure too.
