That Mr looks cool. But right now i'm thinking if i buy a rap4 tank That is small enough i could run a macro to the back of the gun and have it so i could just thread the tank to the macro and then slip the tank into some kind of holster on the stock or if i buy a stock i could slip it inside the stock.
I found this
I think this would be a good candidate for putting it in a mag or a stock. Now if i could only find a hollow stock (such as an mp5) for an mr1.