I am new to the bench rest shooting scene and am having some great initial results- but one thing is somewhat of a problem. I am shooting off a tripod with a sandbag up front and sandbags at the rear. My issue is that my elbow takes a terrific pounding,bruising) even though I rest it on a sandbag on the shooting bench. This only happens with my 7mm Rem Mag- my .223s are fine. Is there a technique on equipment I can use to eliminate this? Thanks for any help.