The repaired frizzen was one of the things that made me wonder if there might have been a gunsmith working on the site some time in the 1800s - maybe cannibalizing some old locks for parts. Hamilton shows some finds like this from Native sites with long periods of habitation. Since this house was built in the late 1700s, and the second lock looks to date well after 1800, I don't mean to imply its a Native site, just maybe someone repairing old guns and maybe peicing together parts worth saving.
On the other hand, for dug pieces, they are in really good condition. Perhaps in 1930 someone might have taken out great Grandad's two ancient, and what seemed at the time worthless, outdated flintlocks and scavenged the locks to try to find a mainspring that would work to repair a third gun and maybe put a squirrel or rabbit in the pot for the family that night. You never know. People do what they need to survive, and people in the region have a long history or being resourceful, making due with what they have, and keeping up old ways well beyond the timeframes we think of as the period of use of muzzleloaders.
Interesting stuff - as TOF said, would love to know more about the site.
Guy