The artist's interpretation of reflections in the highly polished chamber.

Have we seen an Ithaca with the double thick breech?

When you find one, Bill, take a picture of it and post it here.

Which name model Ithaca is that with a square crossbolt? Brown patent rotary bolt guns have a square hole in the rib extension yet this isn’t that because the NID came out way after this. Is this a square version of the Greener round crossbolt?

It is the Lewis Model (1901 to 1906), just a hook off the top-lever that engages the square hole in the rib extension.

I've measured my 6 frame 10 gauge numerous times at the breech but can't remember what it was . I want to say .29" but can't be sure .I'll have to check it when I'm back home .