A battery is just a power souce, as long as voltage is within range and the connector fits, there's no reason it wouldn't work.
mAh's rating needs to be decent so it last at least a game. You probably don't want anything below 1800.
So to answer the question: if it fits in the gun and the connector is the same, yes it will work.
Originally Posted by Brian McIlmoyle
Real life comparison,
GBBR- bang bang -- Giggle
AEG-- merrrzip merrzip -- meh