I remember reading an article years ago about shot alloying and dropping. The author had done some testing of shot hardness of different alloys. Alloys might be a little generous, since the only element, other than lead and tramp amounts, was antimony. If I remember correctly, he was of the opinion that anything over 4-5% yielded no noticeable increase in hardness.
Linotype lead is pretty high in antimony but in the increasing trend to digital information, typeset printing isn't what it used to be, so that source of scrap lead may be drying up.
Electric Boat was one of my major customers, and virtually every casting I made for them required umpteen pages of testing results and certification. In every NAVSEA spec, antimony, arsenic and tin had to be reported, and arsenic was always present, hand in hand with antimony. Those two elements do not break down, ever. I occasionally think about the amount of lead we deposit on all our sporting clay courses, but I guess I will now have to ponder the amount of arsenic (with the antimony) we are also scattering.
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