It's now a reality, an airsoft sentry gun that will watch the fort for you. This is a demo video of a sentry gun made by Scott Bales of Deep Earth Bunkers using an airsoft gun though you can also mount a real steel weapon on it. It's impressive and responsive enough, though it will still need a human operator to identify friend from foe. Now, if they'll just mount an airsoft minigun on it, then we'll all be set for some difficult bunker assault scenario.