Yes, the gun is a semi-automatic. One trigger pull equals one dart fired. At the moment there is no trigger though so it's more like one button push per dart fired.
The only performance tests I've done so far have been rough at best. Range with the gun about flat at 30 PSI was about 115 feet measured with the stride method. Range seemed fairly consistent over many shots (within 10 feet either direction for 90% of the shots). The darts I'm using are too light and I could definitely get more range with heavier ones.
The cycle is rather simple and it is based around a valve assembly I designed with off-the-shelf components that allows for semi-auto functionality. It basically is a QEV piloted and refilled with a directional control valve. It's efficient and simple. I've been considering making a spud gun with a similar assembly, but with a three way ball valve instead of a DCV.
When pressurized the air cylinder (the silver tube) pushes the bolt which pushes a dart into the chamber. When the button on the DCV is pressed, the QEV is piloted and the dart is shot out. Simultaneously the bolt is retracted. When the button is no pressed the pressure chamber and air cylinder are refilled.
There's some more work and a lot of tweaking that still needs to be done but 80% of the work is complete. I won't be able to work on this again until December so I thought I'd post about it to see if anyone has any comments, ideas, suggestions, ravings, or whatever about the gun. This is prototype 1 and I'll be sure to try a bunch of crazy crap on it before moving on to prototype 2.
I'll post more photos and write more about my ideas in a later post.
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