military - What kind of rifle used this shell case? - History

Please, anyone able to tell me what kind of shell is it and what mean this symbol on the bottom ? Is it from 1917?

FN C1 Self-Loading Rifle The Canadian Encyclopedia

AR-15/M16: The Rifle That Was Never Supposed to Be

The Guns of Operation Market Garden

Weapons of World War I

US Troops in Vietnam Hated the M16 So Much They Picked Up the Enemy's AK-47s

Weapons of the Western Front

Cartridge case terminology and identification – Stephen Taylor, WW2 Relic Hunter

The Secret Casualties of Iraq's Abandoned Chemical Weapons - The New York Times

Why police officers need patrol rifles

Weapons of the Western Front

M16 rifle, Definition, History, Parts, Diagram, Weight, & Facts

M134 GAU-17 Gatling Gun

What type of ammunition does the US military use? - Quora

Second World War Weapons That Failed