Before you hunt, check your zero from all hunting positions. A solid rest directs your rifle—and bullet impact—skyward as the bullet sets up vibrations during its passage down the bore. Off-hand, and even in bone-supported positions, the barrel can dip as you pressure the trigger, and as the rifle recoils. A taut sling routinely pulls my point of impact to 7 o'clock. I often zero from slinged-up prone with this impact shift in mind, where on good days I can hold a minute of angle. When one rifle in .300 Winchester printed 5 inches higher at 200 yards from a bench, I stuck with the "sling zero." If you use an improvised rest afield, be sure to pad the forend with your hand, and never rest the barrel on anything. Hard surfaces cause the rifle to bounce, tossing the bullet wild.