I may want to keep this open, because I will be making a Halo shotty soonish. I am actually starting with the gun casing from a House of the Dead videogame. We have some old, busted up ones at work..
Aside from the fact that there are some serious detail changes to be made, I think this will give a decent head-start on it. Also it's nice that all the mounts for the electronics/triggers/pump slide are already there. It will end up just being a conversion job... rather than starting from scratch.
I'll post some images of the gun interior and electronics before I start... I've been wanting to do so for a while here anyway just because it might help some of you to see how these guns are designed and wired.. little details like the design of the trigger/switch mount are really useful fo anybody making Halo weapons.
I'll get some pics here tonight.
-Sean