A "Clunk" or a "Thud" is good. A "Ting" is bad if you are looking for pure lead. I never put much faith in the finger nail test. I am sure there are a lot of guys who are capable of telling how hard lead is by digging into it with their finger nails. But I have never been able to. Also the longer lead sits, the harder lead gets. Regardless of alloy. Tom.