So after finding out that theres a better version of the JG MAC-10 for one-handed use, one that in my opinion would serve me better than both the MAC-10 and the GAT, both economically and in other ways like the field refs not being able to argue with me that a micro uzi isn't a secondary. Thats the gun itself, I plan on keeping the stock retracted and spraypainting the orange tip, but heres the main problem I have. I have no idea how to modify V5 gearboxes, and I want this thing to perform atleast 3/4 of the things an AEG / Assault Rifle could preform. Heres some background, there is no full auto at my field, minimum engagement distance, bang bangs, and max fps is 400. Heres the things I need to know / Would like answered. 1 - How can I change the spring in a v5 gearbox, and could I get it close to 300+ fps 2 - Can I change the cylinder to accommodate a tight bore aeg barrel. (120 - 240 MM) 3 - Can I get a mosfet to be able to use bigger / better batteries, and how. 4 - Can I get a better hopup, and how.