When I encounter lead/lead alloy, that is suspect, I do a not so scientific melt test. I use small pieces of "known" pure lead, as my standard. I then take the suspect lead of equal size and equally spaced on and aluminum pan. I place the pan on a low to medium heat and observe the melt time. I may do this as much as three times. I really don't care much about temperature, just observe the melt time. Of course to start, I give the suspect lead the thumb scratch test.
I also use a home made hardness tester that is less accurate. .....
Be Safe !!!