Peter and a couple others will catch this eventually and let you know about the sunkorite, I think it was applied by local armorers with brush...baked on. I wonder if you should remove the chrome though? That would be an acid bath, I think muriatic acid is what's used. It's toxic as well as harsh so you might want to contract it out if you do that. I've also glass bead blasted it off 1911s that came from central America in the '80's. They blued and parkerized perfectly after.