I will resist the urge to fill this reply up with pictures, but I have had a fondness for Remington 17s for about 15 years now, maybe a little longer. I've collected adds, manuals, parts and currently have 5 of them, though one is a parts gun. I have had a dozen over the years, to include a pristine first year three digit gun that now resides in California with another collector. I have another 1921 UMC 17 still, and a 1927,1928,1931 and 1933. I just recently picked up a numbered 2 barrel set gun with both barrels being solid ribs. It's got some oddities about it but I had to have it.
As mentioned the ribs were machined into the barrels, not added on. They also were designed for the 20ga shell and are a bit thinner than a 37 as the 20ga 37 is just a "short" 12ga frame (all gauges of 37s are the same width to facilitate parts interchanging). The distance between the barrel and the magazine is also less making the 17 slightly more svelte.
What Ithaca did was try to take out as much hand work in the design as possible to maximize profit. Don't get me wrong, this was a very significant task and accomplishment. I do think something was lost in the process though.
The biggest downside is many of them were cut for "kids" guns, and even most of the uncut ones had 13 3/4" LOP. I've found an extreme difference in stocks outside of the standard plain stock and ringtail forends, which tend to be close in demension from year to year. One I have is very modern demensions with only about 2 1/4" drop and 14 1/4" LOP uncut.
