This is fact;
Length of the shot column in a nominal size bore with no shot collar is virtually identical for 1 oz in the 28ga, 1 oz in a 20, 1 7/16 oz in a 16 & 1 3/4 oz in a 12. All of these loads in My "Not So Humble" Opinion are better handled in a barrel with a Bigger Hole in in it. The .410 incidentally with this same length column will have just shy of 9/16 oz.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra