I've made a few for CO2 rifles. for laminate blanks, I used baltic birch and glued them up, it was 3 pieces of 22mm. I got a very nice chuck of beech and a chunk of birch for the others, 6x3" from the local timber yard (atlantic timbers), the lower of the stock and the horn where made from the waste to give more drop. worst part is channeling for the breach, there isn't much room to stand a router and 1" ball end bits are pretty scary. the rest is all rasps, spoke shaves and sharp chisels once the shape is cut out.
have a look on chinese air rifles (google it), there are a few that make them on a routine basis.