9.6 volt battery
 

Does anyone know if you can put a 9.6v battery in a TM M4 S series? Any help would be appreciated.

Sure can, it'll up your ROF and shorten the life of your stock internals and possibly your motor, not to mention you'll need a special crane stock to hold the bigger battery cells, or a sling that holds the battery in a small pouch.

But what do I know, I'm a G3 whore. :p

I ran a 9.6v in my CA M15 (M4) and it killed the pinion gear on the motor in like 10,000shots. But if you must you can get a 9.6v mini that will fit in the SIR grip.