What would cause this to happen?

[Sgtonory]

Traded a guy for a 20# block of lead today and i smelted it down into cup cake size ingots. The ingot as it cooled the top cooled first and then the lead contracted and caused a small hole in all of the 12 ingots i poured I also melted some range scrap and this has never happend with that. The unknown lead is much much harder than the range scrap and has a really smooth and nice shine to it. As for the range scrap it is rougher to the touch and a lot more dull looking. Any idea on what type of lead this would be? 7110171102

[zuke]

It's a softer alloy and that's the metal shrinkage.

[docone31]

You now see the reason for a sprue on molds. It cools and shrinks as it cools.
That is what your melt did. When I melt down, I pour once for the pot. I get shrinkage, cracks, etc... It depends on how cool it all is. Summer, it takes longer to cool.
It is all good.

[Sgtonory]

Ok thanks. Any idea what would be in the lead to make it so smooth? Sorry for the noob questions

[docone31]

Right conditions.
I have gotten many ingots that were smooth and made me proud. I have had others that were ripply, frosty, dull. All manner of things.
It depends on temp, conditions, heat of the ingot mold.
When gold is poured into an ingot, it is flamed to make it smooth while cooling. Lead is no different, just the temp ranges are vastly different.
Absence of O2 can accomplish a lot in a pour.

[Defcon-One]

....The ingot as it cooled the top cooled first and then the lead contracted and caused a small hole in all of the 12 ingots i poured I also melted some range scrap and this has never happend with that. The unknown lead is much much harder than the range scrap and has a really smooth and nice shine to it..... Any idea on what type of lead this would be? 71101

What you described is an indication of a higher Tin percentage. Both Linotype and, to a much greater degree, Solder set up that way. From the looks of your ingot (The one I included!), I would not rule out some type of Solder with a Tin content of over 37%. You might want to get a sample tested!

Also, you can check and see what temperature it melts at. I bet it is well below 500 degrees F, which will confirm what I said pretty easily!

If, and only if, it melts at around 625 degrees F would I consider it to be Pure Soft Lead.

Your other ingot has the classic frosty look of Antimonial lead!