How's this for a crazy theory ?? The hole is there so that a piece of white cloth can be tied on??

IIRC in one of Jim Corbett's books he made mention of tying a white rag to the muzzle of a double rifle. He apparently did it so that he could see the muzzle when hunting a wounded tiger on a moonless night. I dare say he was probably thinking that a 10 yard shot would be a very long one!!

Anyway...who knows. Or perhaps it belonged to an Italian General. ? (ha ha)

Cheers
Rod