How a Johnson rifle works

The M1941 rifle used the energy from recoil to operate the rifle. As the bullet and propellant gases moved down the barrel, they imparted a force on the bolt head that was locked to the barrel. The barrel, together with the bolt, moved a short distance rearward until the bullet left the barrel and pressure in the bore had dropped to safe levels. The barrel then stopped against a shoulder allowing the bolt carrier to continue rearward under the momentum imparted by the initial recoil stage. The rotating bolt, which had eight locking lugs, would then lock the bolt. Following, a cam arrangement then rotated and unlocked the bolt to continue the operating cycle.[1] One disadvantage of this design was its impact on the use of a bayonet, as the complex movements of the barrel would be subject to unacceptable stress when a bayonet thrust was used. The Johnson rifle utilized a unique 10-round rotary magazine and a two-piece stock, the weapon using the same 5 round stripper clips used by the M1903 Rifle.

This system had some advantages over the M1 Rifle, including lower felt recoil and greater magazine capacity. The magazine could be recharged using the standard Springfield stripper clips at any time, which the Garand could not; and the Johnson did not suffer from "M-1 ping," the distinctive sound as the Garand's en bloc clip was ejected that the enemy learned meant the shooter was momentarily unable to return fire.[2] Unfortunately, the Johnson's recoiling barrel mechanism resulted in excessive vertical shot dispersion that was never fully cured during its production life, and was prone to malfunction when a bayonet was attached to the reciprocating barrel. The Johnson also employed a number of small parts that were easily lost during field stripping. Partially because of lack of development, the M1941 was less rugged and reliable than the M1, though this was a matter of degree and was not universally opined amongst those that had used both weapons in combat.