Since the only requirement for sinkers is for them to sink, they are probably scrap, cheap, overstock "bargain" lead. I haven't purchased any lead sinkers in quite a while, (except for a dozen small egg sinkers I wanted for barrel slugging) and those I've seen vary greatly from soft (pure?) to approx wheel weight hardness. I guess the commercial cast sinkers are close to pure but I'd check hardness before I used any for bullets...Please excuse the thread drift , one question and I am outta here.
A guy from the Washington coast gave me a bucket of pyramid shaped fish net weights. What are chances they even have any lead in them?