Forget green lasers. For a home defence, tactical shotgun, a bright white light is critical. Integrated forearm is preferable, but a barrel mounted 6P surefire or similar will work equally as well. With a shotgun, you will want both hands on the gun. For a standard pump action, a pressure tailcap is a good solution. ESPECIALLY in a home defense situation, target ID is CRITICAL. A white light is part target illumination, and part to blind the target. In a dark house, a surefire in a targets general direction will dazzle him enough to gain a decisive advantage. You want a light you can turn on and off immediately. Forget an led headlamp, as stated above its a walking bullseye. You want to illuminate, ID, turn the light off, and move. In a room size engagement...with a shotgun...a visible laser is silly. While a 12 or 20 ga pattern at 10 feet or less can be measured in mere inches, the laser unnecessarially complicates things. KISS get a light, make sure your target is not a family member, and live to fight another day.