It looks like a "guild gun" to me. In the late 1700s and through the late 1800s they had local gun guilds that would offer parts that you could make guns from. My rule is that unless it has markings on it, assume it's a guild gun, and the hammer on this one for sure likes like it is. This is percussion, so it was probably well after 1800, and probably built in upstate NY somewhere. It's nifty but probably not worth a ton. If you see stamps, it could be a foreign guild gun as well. There are a ton of those in the US from Belgium and other countries.