Geo;
Yes it was the Sora I recalled that about. Having never hunted them or in that area, I only know what I have read about them. As I recall the #10s were used only in small gauges with light shot loads. I once had an opportunity to buy an old box of 20ga shells loaded with 3/4oz of #10 shot, probably were 2˝" ones. Don't know why I didn't buy them, they were offfered real cheap.

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