Subcutaneous emphysema is often found in car accident victims because of the force of the crash. Chest trauma, a major cause of subcutaneous emphysema, can cause air to enter the skin of the chest wall from the neck or lung. When the pleural membranes are punctured, as occurs in penetrating trauma of the chest, air may travel from the lung to the muscles and subcutaneous tissue of the chest wall.
Both the Army and the Marine Corps teach that the maximum effective range of the M16A2/A3/A4 is 500 meters on a point target (individual enemy) and 800 meters on an area target (i.e. troops in the open).
Which M.O.A. do I need to purchase? We recommend 0 MOA for shorter distance shooting (0-600 yards). See your scope manual to determine the amount of elevation adjustment or range you have. For long distance shooting we recommend 20 MOA (600-1000 yards). The 20 MOA angled downward mount will allow you to see and zero where your bullet will strike over a long distance like 1000 yards.