I have enough lead, I didn't need this thing. Curiosity won out. Didn't hurt that it's 20 lbs and the guy only wanted $12. Unless it's poisoned with zinc, it's pretty much a no-loss.
But, whatever it's made of, what in the world IS IT?
I tried google image search from every angle. Nothing.
Best I can think is some kind of piston or plug. Those holes for the pin are so high, it couldn't withstand much pulling force. Maybe even too weak to be able to pull a jammed plug.
It looks built to take one heck of a forward pounding. So, leaning towards piston. Or some kind of ram? For what? Pile driver, maybe? It would be easier on the wood than iron, I suppose.
I told the guy I'd come back and tell him if I found out what it is.
I can scratch it with my thumbnail and curl up a shaving with a standard #2 pencil. A COWW ingot will scratch it. But a telecom cable sheathing ingot will not.