It's interesting this topic has come up, as I've been giving it a lot of thought and research. I have a Pope barreled Ballard that I got some years ago from a private seller locally. Sadly, I missed the wave of enthusiasm for single shot collecting and am now trying to sell in a virtually flat market. And that's a flat market generally. Antique furniture, art, and other collectables are stagnant due to these large factors: Folks who care about these things are dying off, and if they haven't, they're downsizing, increasing the market size through divestiture. Young millennials who don't care or know much about history, seek technology and gaming. They buy things that are marketed as green, like bamboo flooring and such. Hunting and shooting are generally in disfavor. Remember that the liberal educational establishment has had their formative years to instill the let's propaganda into our young. It's interesting that the executives of all the tech companies send their kids to schools that do learning via books, paper and pencil. As opposed to public school that uses all the computers, Ipads, and tech those company's said our kids need to become geniuses.
Of course, even with the stock market being in the midst of a downturn, people who have sold off their art, antiques, etc, will still put money into the bond and stock market, just cause it's safer, easier, and a better return.
Just recently I took my Ballard to have it appraised at a local firearms auction house and had a very good discussion regarding all the points I raised and the two reps basically agreed, saying, in part, that most young people are interested in WW2 era and later. Old revolvers? Ho hum, big yawn. Anything from prior to WW2 is selling for practically half of what it once was. Why the big interest in WW2? Private Ryan, Fury, and Call of Duty. Yup, that last one's a video game. So, yeah, economics, social mores, and a diminishing market are gradually shrinking the value on average firearms. Napolean's jewel encrusted shotgun and firearms like that will always be in demand. The Ballard you thought so special? Not so much chum. So too your M1 Garand etc.
It's not all doom and gloom though, it's a good time to buy and enjoy those things you want, as an example my Pope/Ballard rifle!