[BigBoar]

I have not measured them so I do not know if the 6 shot cylinder is smaller than the 7. I do not know why the 7 shot would be bigger. Unless they change the frame dimensions not much would be accomplished as the frame dictates the dimension of the bore to axis of the cylinder. Given the cylinder width then having 6 vs. 7 shots does not change the amount of steel from the bore to outside of the cylinder but will change the width of the cylinder walls between chambers.

If you want 7 shots with the old style barrel perhaps you can find a 686 Mountain Gun somewhere as they do turn up occasionally. They are also 2 ounces lighter than the 620.