My shooting Mechanism needed some soldering so that the tiny DC motor would crank the gears to fire. I soldered up the leads that I needed to, then covered them in electrical tape. This Instructable is a jumping off point, not a step-by-step really, so do as YOU need.
The battery also needed some soldering.
Connect the battery to the firing mechanism and test it, we wouldn't want to put it in the case to find out that it doesn't fire.