Ok, I just got a used mp7 for $100 on craigslist. It needs to be fixed and repaired and this'll be my first time (I have no idea how). Here's a list of what I plan to do: 1. Replace the fuse. 2. Install a tight-bore barrel. 3. Install an external battery (7.2V 3000mAh) Can someone point me onto the right track? I haven't had much lucky searching. Will these upgrades increase the ROF and FPS?