I'm working towards building a nerf gun that looks a bit like the SMG from Halo 2. I have it layed out as being clip fed with a bolt mechanism to que up the next dart, and an air tank as the power behind the punch.
I drew out a nice little picture for you all to get the gist of what im babbling on about:

I penciled in a barrel extension because I feared that having the dart placed so far forward would cause it to fishtail straight out of the gun (short barrel=bad control over fligth path?)
I apologize for the picture quality as I'm doing all this really late at night when i do all my good thinking, and I don't want to distract my room mate wiht a bright camera flash. But I plan[ned] on putting an internal pump in the handle, and the clip in front of the trigger, with possibly another clip stored in the foregrip (small clips obviously for the sake of eye appeal, maybe 6-8 micro stefans)
I also checked out this thread to learn a bit about air tanks.. but I'm trying to not use something as unweildly as a bike pump.
http://nerfhaven.com...?showtopic=8234
Then there would be some sort of bolt action to push the next dart into place. I planned on mimicing the design from the longshot, or at least using it as my model, because i am very content with the smothness of it.
I was also playing around with the idea of an extendable stock on the back, because I had a sudden maniacal thought that i could make this double as a loser-rifle-esque gun by having the option of a longer stock and longer barrel and a sight (and maybe a bipod?).
I dont really know where to begin with this one. Surely PVC frame, probably a brass/copper barrel, and I have no idea how to set up a trigger system on this baby. Any feedback you guys can toss at me would be helpful.