books.google.se - The Browning "50-cal" has become the longest serving weapon in the US inventory first entering service in 1933 and it will remain in use for many years to come. The "fifty" has been employed in every imaginable role for a machine gun - antipersonnel, light antiarmor, antiaircraft, mounted on aircraft...http://books.google.se/books/about/Browning_50_Caliber_Machine_Guns.html?hl=sv&id=TaixfxwdCwEC&utm_source=gb-gplus-shareBrowning .50-Caliber Machine Guns
