I have a Remington model 31 "Lightweight" with Duraluminum action. I don't think I've run into a Winchester. Does it have a light metal receiver or steel? My model 37 featherweights have been all steel...Geo
Featherweight is the name applied to all models of the model 37, up until the company produced the Ultrafeatherweight. The Ultras have an aluminum receiver. Featherweights are steel. There were a few runs of Ultras in the 1970s, mostly 20s, it seems. There was at least one run of Ultras produced at King's Ferry, ditto Upper Sandusky. There is, or, was a 16 gauge Ultra just for sale over on 16 gauge.com, at the not unsurprising price of $750. I owned a King's Ferry 16 gauge Ultra, and mine was a nice gun. I have heard complaints of them being butt heavy, but, mine wasn't. It was, however, scarcely lighter than my mid 1950s Featherweight 16, likely due to choke tubes, knock out wood, and a vented rib the Feather lacked. The Ultra has the same barrel attachment as a steel frame gun, meaning you have steel on aluminum threads, and it would fall into the catagory of guns you carry a lot, and shoot a little. I have moved both guns on. Ultras are not common.
The rare bird out of the 37s seems to be the 3" 12. Also called a Featherweight, it most assuredly is not, my example tips the scales at very near 8 pounds, wearing a 30" ventilated rib choke tube barrel.
I've seen three of them. All were King's Ferry guns. Two had the receiver tapped for scope mounts. This gun is mine, it is a King's Ferry gun wearing Upper Sandusky wood. I sent the gun in when they were offering custom dimension stocking for Ithaca 37s of any vintage, which, they may still do: