Well let's see, 6:30 am when I posted, hadn't had breakfast or coffee yet. Batteries went dead in hearing aid, glasses still are streaked with cutting oil from the lathe work last night., Hadn't even had a shower or shaved, nor scrubbed my teeth yet. and then you set these lofty standards for me and expect me to be able read and answer the questions right. Oh and did I mention I am elderly.
The correct answer to the question is I don't know. But you can buy zinc round balls cast from it for 2 bucks each.
Seriously you would have send Powder keg and email and ask. I have had the mould for 3 or 4 years and I think it was part of a trade.