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).
3,800 Yard Long Range Shot. Matt of Hill Country Rifles sent me this video since I posted about their rifle hitting a 3,600 yard target. Here is there latest achievement, hitting a target at 3,800 yards away. The rifle is impressive. It is a HCR Extreme Long Range Carry Weight .375 Cheytac. It has a custom 200MOA base. That means that the POI is 13ft high at 100 yards.