I just left Griffin and Howe's web site and thought this banner on their home page might surmise for the Original author, an answer to his question.

From their home page:

ADVANTAGES OF A PROPER GUN FIT
Gun will shoot exactly where you point it
Head and eye correctly positioned to rib
No adjustment time to an unfit gun stock
Transfer your concentration to the target, not the shotgun
Hold the recoil to a bare minimum
Reduce your fatigue factor
Increase confidence
Significant shooting score and game harvest improvement

bc