PGK's following a line of reasoning I've been chewing over most of the evening.
The problem with using lead is that, while it's cheap and easily obtained, its shortcomings as a hammer material are obvious. So what alloys with it to make a harder, more durable material without passing into the realms of red-hotness and its attendant dangers?
Tin is one such. But it's expensive and AFAIK difficult to obtain, at least in the quantities desired.
I've never worked with Woods metal – though the prospect of a hammer which melted in the sun is an interesting concept. How hard is it at room temperature I wonder?
Silver/lead solders get a rotten press, might be just the thing here! £ouch!
Do we have any metalurgists aboard?