Each shared a significant number of physical characteristics and common parts, and both operated on the principle of short recoil with a rotating bolt.

The design intended the recoil forces to travel, along with the mass of the weapon's moving parts, in a direct line to the shoulder of the gunner.

[3][page needed] During World War 2, Ally special forces demanded a more portable, lighter, more accurate automatic rifle that provided the equivalent stopping power of the American BAR.

The First Special Service Force commandos, raised jointly with men from both Canada and the United States (the famous Devil's Brigade), traded the Marine Corps 125 of the new Johnson light machine guns for plastic explosives.

Shortly after the 1948 Arab-Israeli War, the predecessor of the Israel Defense Forces, Haganah, developed a close copy of the Johnson, the Dror, in both .303 British and 7.92×57mm Mauser.

Israeli forces found the Dror unreliable as it was prone to jam from sand and dust ingress, and the weapon was discontinued after a brief period of service.

In 1955, he was asked to assist Fairchild/ArmaLite in (unsuccessfully) promoting Eugene Stoner's AR-10 rifle with the U.S. Department of Defense, then with ArmaLite and Colt's Manufacturing Company as an advocate for the AR-15.