W W Gereener stated at least prior to 1910 that the only advantage the 10 held over a 12 was when shot charges exceded 1oz, he highly de-cried the loads with a powder charge of up to 5 drams under 1oz in the 10ga & recommended instead a 4D-1oz load. I highly suspect he was right. Bore capacity of the 10 is only 13% greater than the 12, while the 12 excedes a 16 by 21% & the 20 by 40%.
Statistics are funny things, a smaller % of a larger number is a bigger number! The 10ga is only 6.3% larger than a 12ga BUT it's .046 bigger than a 12ga, .775 vs .729. Essentially equal to the difference between a 16ga and 20ga, .667 vs .615 or .047, although a 16ga bore is 8.5% bigger than a 20ga.
The 10ga was given a greater handicap and eventually banned from live pigeon shooting and trap shooting for reasons. The reason was it was too great an advantage for the man using it.
