Battery to fit RPK stock
 

Okay, so I have a small conundrum with the buttstock I got recently. In an effort to make my AK to RPK conversion right, I got a corresponding RPK buttstock. Problem is, I don't have a battery to fit it.

http://i43.photobucket.com/albums/e3...r/DSC00801.jpg

The length from the inside to the buttplate is about four and a half inches, with about three inches from bottom to top (height). There's room up top for the wiring.

http://i43.photobucket.com/albums/e3...DSC00802-1.jpg

My standard battery for my M14, put in as far as it can go.
http://i43.photobucket.com/albums/e3...r/DSC00803.jpg

I imagine I need a special kind of battery for this, but what I'm asking for is a point in the right direction of what battery I need to buy to make this work.

Any help is greatly appreciated.

considering the room you have, you could get one of these
http://www.uncompany.com/pageproduct...sp?prodid=8211
or this
http://www.uncompany.com/pageproduct...sp?prodid=8211
or this
http://www.uncompany.com/pageproduct...sp?prodid=6514