Improvised weapons can run the gamut from ingeniously effective to one trigger pull away from destruction. Nations in the midst of war will also sometimes reissue obsolete firearms in hopes they will stave off impending doom. Others will find a way of modifying older weapons to meet modern requirements. As the United States fielded the semi-automatic Garand during World War II, New Zeleander Philip Charlton imagined a way how the tiny island nation could have its own automatic rifle by reusing old Enfield bolt-actions.
By adding a gas system to the ubiquitous British long-gun, Charlton would receive a patent for his design, Charlton Light Machine Gun and Rifle in 1941. Not the first attempt at converting a bolt-action into gas-operated firearms, like some during World War I including the Springfield sub-caliber Pedersen Device, but the one that came the closest to seeing vigorous operational use.
Charlton's rifle concept was rudimentary and it worked. Taking surplus .303 No. 1 SMLE Mk3 bolt-action rifles, Charlton essentially added a gas cylinder on the right side of the receiver. The barrel was tapped at roughly the half way point by the piston, which continued past the typical rear of the bolt-action rifle.
The piston was attached to a cam on the receiver that actuated the milled down Enfield bolt handle.Over the receiver handle, Charlton created the cam mechanism which were essentially two forward curving pieces that nestled around the old bolt handle.
This cam mechanism was attached to the rear of the piston rod. As propellant gas pushed the piston gas naturally rearward, the cam allow the old bolt action to rotate up and then back, cycling out the spent case. As the gas dissipated, the piston/cam would slide forward, pushing the old bolt action back into battery.
The resulting rifle had a rate of fire of a fairly controllable 700 rounds per minute, with an overall weight of 16 lbs.
Above is the New Zealand variation including a modified Bren Gun 30-round magazine and forward grip behind a bipod. A number of the modified Enfields were also made by an Electrolux plant in Australia. Those Charltons were more sleek in design, using the standard 10-round Enfield magazine and dispensing of the bipod and foregrip, keeping a more traditional Enfield silhouette.
Some 2,000 Charlton automatic rifles were created. It remains a subject of debate as to whether any ended up in the hands of New Zealand Home Guards. Almost all of the Charlton rifles were destroyed in the years after World War II.