Well, something is wrong with your tests. What? No way to measure your results without a lead hardness tester.
It does matter what the alloy is. Pure lead will not harden when dropped into cold water! The alloy HAS to have both tin AND antimony in it to be heat treated, which is what dropping a just cast boolit into cold water is, heat treating. The addition of a small amount of arsenic acts as a catalyst to improve hardness. Most scrap lead has some arsenic already in it.
When I water drop, I get from 10 to 12 BHN higher than with air cooled. My water dropped range lead is 12-14 BHN air cooled, and 20-22 BHN water dropped. This is being tested using a lee hardness tester. The air cooled boolits can easily be scraped with my fingernail, the water dropped I cannot even scratch them.
As far as the you tube dudes, I don't even bother looking at most of them. Give somebody a platform, then duck! You'll get all kinds of bad info presented as Gods honest truth.
The more people I meet, the more I love my dog
They're going to get their butts kicked over there this election. How come people can't spell and use words correctly?