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).
The maximum range of a BB gun in the 120 to 180 m/s (390 to 590 ft/s) range is 220 to 330 metres (240 to 360 yd), provided the muzzle is elevated to the optimum angle. Steel BBs are also notably prone to ricochet off hard surfaces such as brick, concrete, metal, or wood end grain.