I'd convince myself it's nazi blood and cherish it forever.
Take it to Pawn Stars. They'll have an expert look at it.
Might as well take it to a #### star. You'll get more fun out of it and as much useful information!
I would not clean it.
your gun is probably haunted. you should give it to me and i will exorcise the demon for a small fee
It most likely occurred during ww2 because of the ammo that came with it. The ammo had supposedly stayed with the rifle. The ammo is all Nazi marked. 1939 ammo, all the rounds are marked with the German eagle.
I did not notice the stain until I came home.
Previous owner,... blond hair, blue eyes....
I agree with the others, don't clean it.