Funny, I spliced telephone cable and salvaged a lot of lead. It is NOT pure lead and I suspect most of it's hardness comes from Sb in it. Sleeve lead is softer than sheath and after a year of aging was up around 9 BHN and the sheath aged to around 11 BHN. Never could find anything that gave me a real idea what's in it but it sure ain't pure lead. Sometime I should try a water quench on it and see if it is affected by it. Good rainy day project to keep in mind.