See if you can get the relevant parts of Yardley's book(s) on gunfitting. Much depends on the type of shooting, the gun, and your build. As noted, trap guns are different from... What kind of mount do you favor would be a big part of the equation--like do you mount to your shoulder first and your cheek second or vice versa? I agree with the general fit comment above for game guns for most guys. However, take a look at a gun you shoot well consistently and see what you have there. It may be that you will surprise yourself with toe in or out measurements.
