Does anyone know what the Pendersen patent covered?
As far as the ribs bringing a premium I would guess it's because
they were milled into the barrel, not soldered on. Gil, I did 90% of my hunting this fall with a plain barrel 17 with a poly. It will be my grouse gun for some time to come, although it may not be the looker the Fox was it's wickedly effective. As a game gun it's easy to see why so many were set up this way.
I think Ithaca did make, or intended to make, some improvements such as the second ejector arm on the bolt. I have heard that eliminating the sculpted areas on the frame was a pretty big "achievement" from a production standpoint.
This is an early solid rib gun! It shows a stock extension in progress. It has .018 choke and I shot a 20 at skeet last week with it while trying the stock demensions out. Look out doves!
Here's the grouse/bunny gun