Well, it's a cross between a crossbow and shotgun. A "shotbow", in other words.
The stock is actually a shotgun barrel cut in half so that the shell inside is exposed. The string then goes over the shell and releases it when the weapon is triggered.
Unfortunately the concept has proven to be a little wacky for me to figure out how the darn thing is going to work beyond that.

It would be silly to launch the shell casing since that's not the thing that does the damage. (My brother has since pointed out that the shell is actually facing the wrong way.

) I'll probably just have the casing fly away and the string appear to launch the actual shot. I know it makes no sense at all.
