Practice is the best to tool to use for consistency. I tried grip tape it’s a great reference point, but it’s slower if you miss your index point. It is also slower to slide your hand off if needed. Angled foregrips, broomsticks, tactical Timmy cut down vert grips all change where and what position your hand can be in. IMO find you stock position from collarbone to shoulder pocket, set your lop. Then find the best position for your support hand on the handguard and practice hitting that same spot over and over and over.