I don't think you realize how great the contribution is that you just made. This is a homemade that will go down in the books at the same level as the SNAP. It is cheap, easy to build, and effective. Plus, as you've proven with your own modding, it can be adapted with almost any type of clip, breech, or attachment.
You've made a very notable addition to the NERF community.
This is an example of what can be achieved with some inginuity. Very intuative. A portable compressor or air tank would greatly add to your Rate of Fire. I also love how the person you shot out of the tree is black. (Laugh, I'm not a racist) But don't add a magazine. It will rob your gun of it's most valuable perk, its range.