"Would it be steel or lead shot?
If it is lead shot, whould it also (GASP!) have ARSENIC &/or BISMUTH as a hardening additive?"
Just a thought, but generally lead shot is just that, plain lead. Gives it more throw at the little birdies. Bismuth is a shot alternative where lead is not allowed.
Didn't a lot of cowboys die of lead poisoning back in the 'old days.'