Excellent open reflex sight - Holosun HE510C Elite 1x 2MOA Reflex Green Dot Sight

The large view through this optic is fantastic, easy and fast to acquire a target with both eyes open even in bright light. The green dot alone without the circle is amazing even at 50 yards, and since the auto-brightness function is poorly implemented on this model, you'll want to use the dot-only for use in various lighting conditions.

Note that the LED illuminator is vulnerable to fingerprint, debris, and water. If the LED lens is physically covered or obstructed, the reticle is not shown. For the range and indoors, this optical sight is a blast. For survival outdoors, I would go with a closed reflex sight such as the AEMS.