When I shoot my .375 ruger from the bench I bring my left hand back to the rear bag and don't touch the forearm at all. I rest the rifle with the forearm checkering centered on the front bag. I zero all my fifles that way and havent had any problems. I am pretty sure the bullet has left the barrel before the muzzle rises. I have had some wierd stuff happen when other rests are used, like shooting sticks or bipods.