I have a lot of them that I inherited from my grampa that have not been fired in well over 20 years. All of them are in working condition, and could be wiped down of the protective coat of oil, loaded, and fired if need be.
Last year I found a Wildey Magnum with several barrel, and extractor kits. It is a ton of fun to shoot. Finding brass for it is not fun, or cheap when I do. So it gets to go to the range a time or two a year. I also found some Norma brass for a Sharpe & Hart rifle that has been in the safe unfired for 18 years. I know Norma stopped making brass, and loaded ammo for it a number of years ago.
The .44 Henry chambered in .44 Henry Rimfire has not been fired in over 50 years
. I had it checked by a qualified gunsmith that says it is still in shootable condition. Now finding ammo for it is problem.