Reccommended battery for spartan m4

[vindicare]

Have this spartan m4 from classic army. Takes small types and the stock battery that came with it doesn't work. Another generic battery doesn't work either. Is it a provlem with the gun? What would be a good type of battery to put into this airsoft rifle?

[T6e9a]

Typically, a 9.6v battery should do well. On a full charge, and it still doesn't work, there might be other things that are (or not) going on.