Demand is pretty steady for Smith & Wesson and Colt revolvers. Folks don't like the trigger locks and buy the pre-lock Smiths often at premium prices. Also, many feel the older revolvers are better made than the current manufacture. Folks are collecting the older revolvers. Hence prices keep going up. Ultimately, the moderating force on Smiths in general is the price on current manufactured revolvers. But you can't get that wonderful deep high polish blued guns these days as new guns. I have not looked at any of the Smith Classics however to compare the bluing.
As far as shotguns go, most people don't buy a lot of shotguns but they may buy more than a few handguns. Demand is less.