O/U
Well speaking for myself, I was shooting trap with a 500 which was pounding the crap out of me and seemed to be doing the same to the gun, which was made back when they still had some decent quality. I kinda fell under the influence of the old timers at the club (who told me to buy browning), and went with a double I could afford. It really does shoot much nicer than the 500. It has ported barrels and is the 28 inch extractor model. I have since learned pretty much what you said, stick a Birchfield-Casey shell catcher on the side of (whatever) semi-auto and away you go with very little kick. I think the o/u craze is a bit of group think now that I have experienced it.
Anyway I took the gun down to the internals and blasted it with WD (blu-torch) let it drain and wiped it down and then blasted it with Rem Oil in aerosol can wiped it down and re-assembled it. It's still stiff, but, it doesn't seem to be "cranking" it down when you open it. And it doesn't feel "wrong" like it did before. There wasn't much crud in there, but now there isn't any crud in there. (don't worry I put some empty shells in there before I dry fired it). I am just breaking it open with a firm smooth crank and seems to be performing acceptably