Well I actually ended up buying a cheap $12 airsoft gun. It worked pretty perfectly because all the outside was metal, which was what I wanted, but all the insides were plastic which made it easy to work with.
Anyway, here is the finished product. I will have better pictures soon.

In pieces

Removing the metal barrel. I recycle this piece and use it to hold the Aim-Trak sensor

I put one end in a vice and tightened it till the end could fit underneath the part the held the barrel.

The part that will hold the sensor... basically the barrel cut off and moved down.

About what it should look like

Used electrical tape to hold the sensor on. The wires run through the barrel hole, out the bottom, through the clip (where the trigger button is, I will show you that part latter), and out the bottom of the clip.

The new and improved barrel attached

Completed gun
Don't worry about that ugly bolt sticking out. It will be removed soon. Besides that the gun looks and feels amazing. Now just gotta be bad and scratch off that orange paint
