Roger, I have a 12 gauge Ideal and have wanted a 10 gauge (and a 16 as well). I watch the Naturabuy auction site in France where at any given time there is 80 to 120 Ideals for sale. In two years of watching I have only seen one 10 gauge. They made them but not many!
I am not a fan of the lunette triggers but want the gun for hunting sharptails with light 10 gauge loads. Given the way my 12 handles I guessed the 10 would be a pretty light and good handling 10 gauge for that purpose.
I have the book on Ideals....have not been able to find anything there or anywhere about production breakdown by gauge.
Would love to hear how it is in the field.