Zombies can sure be a pain to kill; hopefully this information will help. Equip the shotgun, then enter "first person view" by holding the "R" (look) button, use the "C" buttons to move around, when you want to fire, hold the "Z" button and use the red laser to aim. After you have fired the first shot, press "Z" again as you see the sparks (from the first shot) dissipate. If you did this right, Conker will not lift the gun, but will keep it at the firing level to reload; and, if you really time your shots well, Conker won't have to reload the gun at all!