I wouldnt think it would be safe to shoot. However it may have a valuable history, depending on where you are and if any family members know of where it came from or why it is there. I would be asking everyone around if they know the story of it. People dont just throw something like that down for no reason.
My advice would be to not attempt any repairs or modifications to the gun until you find out its history, then mount it in a frame and hang it on the wall.
Whittington Center Life
Times are tough, ammo is expensive, there will be no warning shots.