I wonder if vinegar would work better. It will remove salts and base contamination but I found it etches lead good and may add porosity to the surface for better adhesion. It also produces the white toxic solution that must be handled carefully but I had an experience with HCL I don't want to repeat. the posted 'hammer' tests look much like mine - pounding on the concrete floor will cause some chipping of the coating. They still shoot good.