It's possible to find a gun called the Chauchat, a joke weapon that does no damage and cannot be fired. The gun itself is based of a real-life Light Machine Gun used by French and American troops during World War I. The American version of the gun was infamously unreliable, due in part to manufacturing issues and the effects of muddy trench conditions, to the point that even in perfect condition it could jam just after a short burst of firing. The weapon's item description calls it "the worst machine gun ever" in reference to these issues.