I'll stick my head in the sand and 'believe' its been their since the 19th century.
Anything is possible but the round found in the buttstock was made between 1899 - 1911 so that narrows it down.
It’s also interesting the round was found in the buttstock cleaning kit recess, like maybe someone had no idea how to load it and shoved a round in the butt a ‘la a Spencer carbine.
The fact that it was not loaded when found is odd but not unusual.
If it was used for hunting and an animal was taken it was either the last round or the owner unloaded it before setting it down.
Another thought is it was a ‘loaned’ rifle and the user, not being the owner, was irresponsible and left it.
Another could be it was a kid ‘borrowed’ the rifle from dad, shot the remaining rounds up and forgot it in the woods.
Stolen is another possibility.
Rifles left in the woods are not particularly uncommon as I have known of a few people over the years who have found one, leaning against a tree - I also know of a couple who have left them as well....
