However the cold hard facts easily explain why the 10ga lost out in the popularity race to the 12. Until you get to heavy loads of large shot, it simply holds no real advantage over the 12.
The only cold hard fact is, you are wrong. Perhaps the 10ga you owned and shot would not outperform a 12ga. My experience is pretty extensive and my observation is 180 degrees opposed to yours. A bigger bore performs better.
Your 13% formula is still a large difference when it comes to a shotgun. It means the surface area of pellets affected by bore scrub and the height of the shot column being equal for crushing the bottom layers of pellets makes the 10ga with 1 1/4 ounce equal to a 12ga shooting 1 1/8 ounce.
I am hoping the original poster is not discouraged by your advice and I hope he notes it is contrary to most eveyone here who has put a 10ga to use on game and clays.
