This gun is powered by elastics attached with string to a wheel, which in turn is attached (by the same string) to a white connector that acts as an anchor and spools the elastic around the wheel. When the trigger is released it spins a series of gears which are set up to multiply the speed of the spinning gears at the front of the gun (6 times faster at the front row than the back row). It fires gray connectors from a magazine by making the rounds come in contact with a treaded spinning wheel. The friction from elastics pushing up the rounds against the rubber treads provides enough friction to push the connectors out at speed. Currently, however, it has 1 foot of range. This is because a: a lot of energy is lost by spinning the crank when it fires, and b: the tan connector that holds the gear in place on the rod with the crank attached pops off it there is too much pressure, so I can't increase the elastic tension. I tested this without the crank and it got about 4 feet of range. If the crank and tension limitations can be overcome 20 feet of range seems achievable. I didn't bother putting a lot of work into the way that the mag attaches to the gun because I decided to ditch this version.
I'm posting this because I wanted to throw it out there for people to think about. There are a handful of new concepts within this design. I think I'm going to be tearing it apart to build a derivative version based on what I've learned here.
UPDATE: New photos and a new video is up. The new photos start at picture 15. I made the crank capable of being slid back and forth to disconnect it from the gear system and eliminate the problem of wasted energy. I made the gun wider at the back to make room for more structurally stable mechanisms. I changed the gear that the crank rotates to a smaller one so that it is easier to crank and is capable of winding the elastic back further. I estimate that the treaded wheel is now spinning about 4 or 5 times faster (just a guess). However, the gun still gets 4 feet of range. This seems to indicate that the treads on the tire only provides enough grip to fire 4 feet no matter the speed. Therefore, I will be creating an alternative firing mechanism. But don't worry, I have some ideas that should work. 20 feet of range is looking more and more attainable.
Here's the new video; http://www.youtube.com/watch?v=BX_y5pM_lXA
For some reason, embedding isn't working right now.