The advice I hear (and read) most often, and what works well for me, is to grip the pistol grip very firmly and pull the rifle back into your shoulder, thereby making it easier to relax the supporting arm. That is, a right handed shooter tries to relax his left arm and let be simply a pillar. When I let the right hand relax I find the muscles of the left arm coming into play to support the rifle, not good. I've been told it's ok to squeeze a little with the left hand to discourage muzzle jump but to avoid pulling back with the left. Hope this helps.