tungsten probably would be good. It weighs about the same as gold and has a high melting point.
What about resistivity compared to standard copper, and price compared to something like stainless steel, or perhaps chrome-plated slugs?
We ARE talking about something that would be workable from a hobbyists or gunsmithing bench, or at least that is why I posted the article. Something that anyone with some decent tools, preferably not demanding something greater than a small machine shop, might be able to construct.
Plus, I am not sure how available tungsten is or how expensive it would be to purchase and experiment with.
Tungsten is a very poor conductor though, hence its utility in light bulb filaments.