.007" and .013" ? Pshaw, Bob, them ain't that tight!
I've got another .410 S X S with screw in chokes. They're marked C, IC, M, IM and F. The three tightest constrictions, as measured by me, are .012", .023" and .034". I've never even tried to pattern the two tightest ones. Got no idea what kind of pattern they would cast, but I've got my doubts about their usefulness. Hallowell designates .018" - .021" as Full in a .410. I guess .034" would be XX Full.
My Dickinson is fixed at .008" and .008".
My Yildiz is fixed at .011" and .015".
I've killed piles of doves with the Dickinson and Yildiz.
