I have lead molds and this is nothing like any I have ever seen.I think it looks like a mold for making lead fishing weights.
I'm wondering if it's a Piloncillo (Mexican brown sugar) mold? Sure has the cone shape that piloncillo has. Hope the image shows.
Marty, I think you are onto something. The shape is right on. I linked to that one on ebay and it looks exactly the same, or is it the same one we've been talking about? I think you win this one.