ok so i have a kraken ak-47. nothing deadly i know but i purchased a new battery online, a 8.4v 4000mAh ni-mh. it originaly had an 8.4v 1200mAh ni-cd . my question is will this increase in mAh will it strip my gears if i put it in. and do i need a new charger or can i use the one that came with the aeg.