I need to spec out a material for a small sensor housing that can block gamma radiation. The radiation shielding specification requires an alloy containing at least 85% lead, but I get complaints from machinists when pure lead is specified since it is too gummy to cut with decent accuracy. Most lead/tin solder alloys don’t contain enough lead, but I was planning to specify Antimonial Hard Lead, which is 93% Lead, 6% Antimony, and 1% Arsenic and other trace metals. It is typically used for making battery plates, but I can’t find any information regarding its machinability.

Can anyone with experience machining lead alloys suggest a better alloy?

Thanks,
Joe