So, I'm just gonna gut an AT3k for it's valve, hook that upto a pressurized gas either Air or CO2, and have the auto cocker ram and what ever cycling the bolt. That'll make things alot easier. Might even put the whole thing inside my longshot.
I don't think a plastic air tank will work with CO2 or compressed air.(it might explode) You could probably use a regulator.???
Here is a mod for a brass eagle paintball gun to fire nerf darts: Yakman's paintball mod
I also play paintball and nerf. I have a tippmann 98 custom