Is adding a thicker recoil pad the only legal way to lengthen the stock of a cowboy silhouette rifle? Is that even legal on a smallbore rifle that obviously doesn't need any recoil dampening? I need about 3/4" on my smallbore and pistol cartridge rifles (22lr and 22mag). After making the Frankenstock fit me and seeing how much better it felt, I need to find some legal way to make the stocks on those Marlin 57 and 57M that I use for cowboy silhouette fit me.

AFAIK spacers between the stock and the buttplate/pad are accepted.
I don't believe that you can modify the cowboy stock except for LOP and
IMO the rule on this is fine as is...
What did you want to do?

I just want the stock to be longer.

Edit: Sorry I wasn't clearer in the first post. I do not want to change anything about the shape of the stock, as doing so would violate the whole premise of the cowboy match. I'd actually be pretty disappointed to see custom stocks allowed on cowboy guns like on hunter class guns in the scoped rifle matches.

Bump for the edit.. was going to moved the text from the edit to a new post, but this is easier.