My Type 56-1 does this same thing, and its the one thing I hate about it... the fucking lack of space for all batteries except stick LiPo's! You'll probably have to sand the gas block down a little for an easier fit. I'm stuck taking the upper hand guard off and sliding the battery in that way.
Guardians of Asgaard - KF25 -
Primaries: LCT AS VAL, Real Sword Type 56-2, VFC M4 CQB Mk2
Secondary: Latino heat, TM Glock 17