Here's my opinion for what it's worth.
I personally would not shoot a 200 year old gun for several reasons. First of all, with the number of modern made, high quality contemporary rifles that are around today, there is simply no reason to take a chance on destroying a valuable piece of history. Sure, you could probably find a 100 year old man who would be willing to try a 100 yard dash, and yes, he might make it to the finish line, but then again he might not. Why chance it.
The other reason for not shooting it is strictly monetary. If you have a poorly made half stock that only has the value of a few hundred dollars, if it blows up you'll just be out an old gun (and maybe some fingers or worse), but if you have a high quality relief carved golden age rifle that's worth enough money to put your kid through college with, why would you take the chance on damaging it and lowering it's value?
With all of that said, it's your gun and you can do what ever you want with it, and that includes using it for firewood. But I think we are all just temporary caretakers of these important pieces of history and we should be the best caretakers we can be while we own them. Just my two cents.
Frank