[MadMax]

Higher rated batteries will be able to fire more shots. On a bulk scale, higher mAh can sometimes indicate a lower internal resistance so a higher voltage is delivered to the motor. However, capacity is often traded off with internal resistance if you stick to the same cell and technology. Because of technological improvements in batteries this hasn't been the case in the past few years. I used to be that there was a tradeoff between IR and capacity but because cell design has improved significantly the tradeoff hasn't been much of an issue. Pretty much any sub C cell has a low enough IR to drive the relatively low current requirements of airsoft guns.

The super current demands of RC cars had dragged rechargable batteries past what airsofters need so we can enjoy high cap batteries that have low resistance now.