Well harcore newbie...I ran into the same trouble as you did. I have an ICS m4 and when I got OFCOURSE....wanted more power! :twisted: So I popped open my split gear box muahaha...replaced the spring guide, spring, and installed some metal bushings. BUT it stuck when back together.
Now this was months ago.....its true that some batteries just wont push it. BUT i found that the anti-reverse lever was my problem. When installing gears the sector gear's tappet nub shoulb be at a 1:30 position. Well i didnt pay attention to this after installing my bushings. BUT moving it changed how the sector gear acts with the ARL. It was causing the lockup when the ARL kicked in probably near the last tooth on the sector/piston at nearly full spring compression, causing to much torque for the Motor/battery to over come on the next pull of the trigger. So I opened up the lower gearbox...adjusted the bevel gear a few teeth and put the sector gear in the right position. (gear position is crucial) VUALA!
OH and wanna solve those CQB problems....get an ICS with one stock upper for CQB and one upgraded upper for outside.....or just have your trusty KJW g23 with ya.
Now I would say keep that gun stock for a while....test it out. Dont make mistakes about getting into that gearbox in a hurry and screwing something up, like me
Id say for now....your best bet is invest in a tight bore barrel, and maybe a better hop up bucking....those will help with accuracy and a bit with FPS. IF you MUST upgrade some internals....just look at maybe some metal bushings and upgraded spring guide.
OH and by the way....im new to this site....live in arizona (Junior at NAU but am from phx)....I WANT TO GET INVOLVED!!!!