The internal pictures didn't come out. I'm really angry about that, but it's too much of a hassle to open the gun back up. Anyways, the 1500 tank is located where the forestock used to be. This is also where the foam is in the front of the gun. You can see the PETG barrel coming out of the front of the gun.
The gun is fired by pulled back on the large, foam contraption at the back of the gun. This pulls the firing pin. I can't explain the setup. Basically, I took an old barrel peg. Not the air restrictor type, but the kind the dart actually slides over. Since these are hollow inside, I wrapped the 1500 firing pin in electrical tape, and slid the post over it. With a little hot glue, it was secure. Then, I wrapped an electrical tie around the little plastic bend on the top of the barrel peg, and brought it out the back of the gun.
See the holes on the top of the barrel pegs? I stuck the tie through there.
Anyways, I also got the pump tube to come out the space in the back of the gun along with the firing mechanism. The reason there's a space there is because in the Expand-a-Blast there's originally a stock that pops out. After removing the stock, there plenty of space to toy with.
Anyways, here's the finished product from the side and user's point of view. Once again, I'm sorry that the internal shots didn't come out.
<EDIT> I found the following picture: it's the internals of the gun. However, this is an outdated shot. The whole "air restrictor" firing mechanism is not there yet. Just to let you know, this original design was faulty, but I'm just posting it so you guys can get a general idea.
