As I've said before, I found myself stuck with a surplus of orphaned Mavericks over the course of our Nerf misadventures. I even got one and eventually reduced it to a single barrel. That was fun and all, but I felt like I could do so much more.
One day I found out that the Titan, a giant rocket launcher-style gun, actually has some rather compact guts for its size. In fact, it turned out they fit somewhat nicely into the envelope of the Maverick. I had already modified the barrel on mine to fire darts, so it was obvious what I had to do.
The main pressure chamber has a small plunger that is tugged back to fire. The easy part is connecting it to the trigger, which I managed to do with some floral wire. The hard part was making sure it could spring back to the closed position.
I must admit this is a kind of lazy job. I thought of making a pair of wooden forms to hold the pressure chamber and pump in place, but then paracord happened. I might try that again later since the cord on the pump interferes with the stock rocket.