gamoUSA use wont sell you one. they wont sell the newer style of stocks yet. i have a viper express that i despise very much and so i stuck my big cat's action into it. it does fit. all i did was pull off the bigcats original end cap and put the express's new style cap onto the bigcat, dropped it in the viper's stock and bolts up same as all the other gamos. they(gamoUSA) are telling to turn around and go back the same way where ya came from thats all. they won't even sell you the cocking lever rollers or the o-ring for the cfx's rotary breech loader. check out T.W. chambers in england. if they don't have it yet, they will have it soon. they haven't failed me yet.
http://www.gunspares.co.uk/