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).
According to FN, the 5.7Ã28mm cartridge has an effective range of 200 m (219 yd) and a maximum range of 1,800 m (1,969 yd) when fired from the P90, and an effective range of 50 m (55 yd) and a maximum range of 1,510 m (1,651 yd) when fired from the Five-seven.