The Browning M2 heavy machine gun is an American designed weapon that fires "fifty caliber" bullets -- bullets 12.7 millimetres wide.
It was designed by John Browning and remains in front-line use by military and constabulary forces around the world.
Stacy Glaus (2011-01-27). "A legacy of innovation". United States Air Force. http://www.hill.af.mil/news/story_print.asp?id=123241197. Retrieved 2011-05-28. mirror
Richard L. Baird. "The Guns of John M. Browning". http://www.ogca.com/guns_of_john_m_browning.htm. Retrieved 2011-05-28. mirror