Agreed. Not sure what would’ve been fired from a brass barrel in more modern times. Small caliber rim fire? Lack of any ornamentation seems to speak against it being a toy but honestly it’s not like anything I’ve seen before. I agree that the style of barrel and sight look more late 19th early to mid 20th c. Have dug many cap guns before, as well as pistols and weapons going back 250 years here in Louisiana, but no toy guns that were plain and unadorned. Found a hammer from a percussion cap musket in the same field today. It’s a mixed site.