I've been using the Kent Tungsten Matrix in my old SXS 20 for years. I's safe to use in the old guns and hits much harder than bismuth. At 10.8g/ cc the Tungsten Matrix is much closer to lead than bismuth 9.8g/ cc.
I bought a bunch of it, Natchez had it on clearance at some point around '02-'03. I think I bought about 400 rounds of the stuff. Down to my last 10 boxes. It was right at a dollar a round when I bought it.
I have loaded lead, and shot it alongside Tungsten Matrix and could tell no difference between the two. That was as recently as last year.
I guess when my supply runs out I will have to look at bismuth. I shot bismuth in '94ish when they first approved it and it worked fine. The clearance on the T-M was just too good to pass up.
