I made a crude jig out of steel bar and clamped it to the sides of the slide, to prevent any mistakes/slipping & to limit the depth of the initial grind, then gently hit the slide with an angle grinder, just to take it down a bit. I then removed the clamp/jig, and slowly worked it with a flat metal file, testing often to see when the mount would clear, so I would'nt remove too much. This worked well, as the mount fit firmly in place when I was done filing. I hit that shiny spot with a little black paint before final attachment of the Henning mount with provided set screw & put a little blue loctite on the set screw and tightened it down, then mounted the Venom red dot.