American WWII - 50 Caliber Casing “SL 42”
Made of brass, these rounds were shot by Browning M2 machine guns, widely used by American bomber and fighter planes in WWII.
The markings of the head-stamp code show the letters 'S' and 'L' along the top and the number '42' along the bottom.
(The number '42' - produced in the year 1942.)
The 'S' and 'L' denote that this bullet was made in St. Louis Ordnance Plant in St. Louis, Missouri, by the United States Cartridge Company (a division of Western Cartridge Company). This company manufactured 6.7 billion of these cartridges for WWII.