I have discovered that the process I went thru was way to involved for the common caster to fool with. I had equipment that the average Joe would not be able to get his hands on. I still would not go thru again it unless it meant not shooting.
I also had discovered that I had the wrong mindset. What I was doing was removing lead from a Zink alloy not vise versa, leaving me with pretty much pure lead that needed to be alloyed again with a little tin to get it to cast well.
Had a fellow Join here from another sight who who tried to do what I did with a common set up, He got bullets that did not cast well, I am betting he had almost no tin content, also. He threw in the towel, can not blame him.
Of course with a small amount of contamination why not just water it down, as you need to alloy for tin anyway.
I no longer have access to the test equipment I used for my test, as we sold our old spectrometer. We are only running equipment calibrated specifically for aluminum alloys right now. Or I would have had him mail me some to test for him.
I believe, Where Zink bullet casting will find its place, will be in air gun hunting. After being woke to the advances in air guns lately.
Seems the fellows who have made the bullet longer. To get a good weight and more stability. They have been taking the lead in Making zinc work well. This becomes a problem with cartridge, bullet seating, length. Finding the right powder for the smaller space, and so forth.
I am just betting in a few years there will be a Group of fellows dedicated to specifically Alloying, casting and powder coating zinc bullets that will be able to realistically, and efficiently take down large game, out of an air rifle.
The problems eventually, will not be if it can be done correctly. But if hunting regulations will allow it, and if the Feds will leave them alone or start regulating them as a fire arm.