My Joseph Lang was built in 1866 and I have no Idea how much it was used before I bought it. I've shot over 6,000 cartridges in her and she works as well as ever. I shot quail with her Friday a week ago, 100 rounds of clays this past Friday and am taking her quail hunting in Georgia next Saturday. I fully expect someone else to be shooting her regularly after my demise.
I also have a J Lang hammer gun from about the same time. Inside the locks look like stainless steel, they are so highly polished. Every thing tight and working fine. I put about 500 rounds through it a year. I doubt I will wear it out.