Okay, I'm stumped on this one. Found what appears to be a lead nail today at a colonial site. What would you use a lead nail for and how would you drive it into anything? Maybe it's not a nail, but it sure looks like one to me! Please enlighten me on this one!
I know that lead was melted and then poured into a joint that connected two cast iron pipes. Then the joint was sealed by tapping the lead further into the joint with an iron tool. Your "nail" may have been a poured joint of some type.
Could be used as a fastener for lead sheathing on an old wooden sailing ship. Some ships hulls were sheathed to stop worms from eating the wood. Link below explains the problem of iron fasteners.
My other hypothesis was it was from a lead roof on an old building. A lot of old churches in England are sheathed with lead. Here is another lead nail posted on T-net...
Boy, I don't know what is was used for now! It does have a point like a nail, so I don't think it was used to connect joints. Possibly a survey marker, but why use lead? Guess i'm going to have to do more research on this one...