Custom stocks DO have many of these changes, starting with more Cast Off, and then adjusted combs. Most Trap shotguns, and those made for Skeet shooting come with adjustable stocks for pull, and comb, and to some extent, pitch. The guns I refer to are specifically made to be used in these clay target sports. The Trap guns are single barrel with high ribs, and adjustment in the stock for comb height, pitch, and pull. Some are designed for a two barrel set, with one being for shooting singles trap, and the other for shooting doubles. They will always be in a O/U configuration, and will also have adjustable triggers, and stocks. They are fitted with screw in chokes, are often back bored, ( a 12 gauge gun has 10 gauge bore most of its lenth, until you near the choke tubes in the muzzle, where the bore tapers down to 12 gauge. Back boring reduces shot deformation, reduces both pressure and recoil forces, and the gently squeezing of the tapered board elongates the shot string as it goes through the choke tubes, where it regains its original lenth before exiting the muzzle. This produces tight patterns for long range shots. ) Check out guns made by Kreigoff, Ljutik, Perazzi and others. Briley is probably the most famous of the after market barrel makers, choke tube makers, and customizers of guns for shooters. I believe that company is in Seattle, Washington.