I made three large (50lbs+) ingots out of range scrap and some unknown lead. The range scrap ingot (1) rings nicely with a high pitch. The ingot made with mostly unknown lead (2) has a dull thud sound with little ring. The third ingot is mostly range scrap, and has a slightly lower ring than the first.
The ingots were made the same day and all were cooled the same way. (I turned off the heat)
I am wondering what the second ingot in made of. The dull thud has me thinking it has something else in it like tin, I am hoping tin. If anyone has large ingot of tin, linotype or other known material, please smack it with a hammer and describe the sound. I am sure this test is subjective, but any info will help.