Brickguy, those grips are meant to be used for the semi fingertip drilling. The hump would actually fit right at the first joint as the fingers are inserted deeper than with full fingertip. We use them in the full fingertip drillings, however, & the bump actually contacts just behind the pad of your finger. If you take the point of your left thumb & apply pressure below the last joint in the finger, you will be able to see how the bump works. I guess you need to also kink the tip of your finger & apply pull pressure. Also, those grips are just very comfortable.
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Wayne
Hardcore FOS
Rom 2:2 Professing themselves to be wise, they became fools