I am a commercial caster. A few years ago I had a local plating company plate a few thousand bullets. The objective was to see how thick the plating should be to eliminate leading, ie to do the same as jacketed bullets. I found that two thousandths was enough. Strings of 100 fired from a 9mm and a 357 Mag left the bores clean with no leading at all. I never took it further because having an outside contractor do it was too expensive, and the equipment was too big for my small workshop.