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).
Confidence votes 20. The US Army defines the maximum effective range of a .308 as 800 meters. The US Marine Corps defines the effective range as 1000 meters. There will be variances due to things like bullet weight, barrel length, etc.Generally speaking, bullets are no longer effective once they become subsonic, which happens at around 1000 meters with a .308. Maximum Range - 3,600 meters   Max Effective Range for a Point Target - 500 meters   Max Effective Range for an Area Target - 600 meters   source: Army FM 3-22. â¦ 9 Apr 2003 / 2-1 / PDF 27.