As I understand it the 96:1 ratio was primarily based upon considerations of recoil. This was I think based upon giving the gun using a standard powder charge for normal velocites a recoil velocity of approximately 15 FPS. Burrard in his most excellent book does not mention the shot wt to gun wt ratio at all but confines most of his data to the gun's recoil velocity. The 12ga 2½ "Low Velocity" load giving 1¼ oz shot a MV of about 1050 FPS has less recoil than does the Standard "Game Load" consisting of 1 1/16oz shot @ an MV of about 1270 FPS. The 96:1 ratio takes no account of MV's at all so is somewhat limited in scope.
Burrard stated experience had shown most shooters found a Recoil Velocity of about 15 FPS comfortable, while one of around 16 FPS was about the limit most would be willing to endure except for very limited shooting.
