"When you grab the Kettlebell handle, make sure you grab with the fingers, rather then squeezing with the center of the palm. Complete the grip by hooking your thumb over your first two fingers.
Remember, a kettlebell is a fixed weight and so the progression is
through more volume (repetitions). A crushing grip, when you squeeze as
hard as you can with your palms, is used for heavy lifting such as a
barbell deadlifts, but would cause your grip to fatigue very early in
high repetition Kettlebell lifting. That's why we grip with the fingers
instead of the palm."
- Steve Cotter / Facebook / 01.07.2016