It was definitely a flintlock. I had the year wrong, though. I was actually looking up information about the gunmaker, and he died in 1849. It could have been 1821, or maybe 1831. My aunt has a handwritten note about the history of the gun written by my great, great grandpa. She keeps it with the powder horn and a patched up possibles bag. Where the date is written, the 3rd digit in right on a fold in the paper.
She actually has a picture of my 3rd great grandpa Miles Singleton holding the rifle before he went off to fight in the Civil War. He was holding that gun, and it is clearly a flintlock in the picture. I don't think he took that rifle to fight in the war, though.
The lock was converted to a caplock. The prime pan was sawn off, and you can see where the main spring was. A friend of mine, Don Bruton, looked it over with me the day it came into my hands. We partially disassembled it, and he pointed out all the changes made to the lock. He's a master gunsmith and has handled who knows how many original guns, so I'm confident he knows what he's talking about.