The MP18 (Maschinenpistole 18) is a firearm designed by Hugo Schmeisser, the very first open-bolt submachine gun ever. Predominantly chambered in 9×19mm round, it was introduced in 1918 by the Imperial German Army during World War I as the primary weapon of the Stormtroopers. Its design became the basis of most SMGs manufactured between 1920 and 1960.
Unlike more modern SMGs, the MP18 featured a wooden rifle-styled buttstock without pistol grip, and relatively heavy due to thick milled receiver tube. Magazine is inserted on the left, and can accept the 32-round "snail" drum magazine designed for the Artillery Luger.
This tag implicates submachine_gun (learn more).