What stock for larger batteries?

[Drewcole81]

Hi all,

I have a G&G GR15 AEG that I run on 9.6v 1600 mAh batteries, I would like to change the stock so that I can fit a larger mAh pack into it say a 3300 set...

I've had a look around but not really sure which ones I need to be going for or weather I need to change the tube as well.

If anyone can point me in the right direction that would be great.

Thanks

Drew.