For the stock, you can see in this web:
http://www.trapperindustries.com/airsoft/page12.html
To more battery, it´s necessary install the metal front set and make various modifications, in my ak47s and my ak spetsnaz S I have installed the metal front set.
When you have install the metal front set, you must make this modificatios in the gun:
http://miarroba.com/foros/ver.php?fo...temaid=3720576