I used Kasenit years ago on the sears of a Billinghurst type underhammer pistol I built. I also used it a couple times to case harden nuts that I drilled reliefs in to make thread chasing dies. Hard N Tuff and Cherry Red are other brands of surface hardening compounds. Once I used regular table sugar as a surface hardening compound to make an emergency thread chasing die, and that worked too for the single job I used it on.