For a using old double, I have shot L.C. Smiths the most. It depends on the gun, and I was lucky enough to find a really nice Hunter Grade with what I think was new stocks on it, but I am not sure. At any rate, it's been rock solid and I have shot a lot of heavy high base 6's in it, shooting Pheasant., and also lighter loads shooting backyard Trap, hundreds and hundreds rounds and it's still as solid as a rock, both wood and action.
I have owned several L.C.'s and some are better than others, all of them seemed to have solid lockup's, but the wood on the old guns can be weak, and I have one extremely lightweight 12 ga that I had to have the stock repaired on it, and this gun is a higher grade but should not have heavy loads used in it, I think.
I have a Winchester 23, and it's what they call a Pigeon Grade, actually, I have two if of them, both shot a lot by me. They are good solid guns, and even have 3" chambers but kick like heck with 3 inch shells and I would not recommend 3" shells for them but 2 3/4" high base 6's no problem.
I have a J.P. Sauer, probably my favorite upland gun, It does fine with 1-1/8 oz 6's. It's a fine gun but very tight action and can become hard to open if hot from a lot of Trap shooting, but never under hunting conditions.
Have a Parker, wonderful old gun, in great shape. But they have a lot of parts in them and not just any gunsmith can work on them, and I have seen several, not mine but others that needed some work done on them, after a lot of shooting.
I love side by sides, but the old ones can be finicky about ammo and they don't like some of the cheap Wal Mart promotional ammo, because I suspect the firing pins sometimes stick in the primers after firing. You need to spend a little more money for better ammo for a lot of the old doubles. They all seem to shoot AA's pretty good, and the Remington better quality shells. Some of the guns don't like Federals or the really cheap Winchester ammo.