Strange Guns (formerly Rare, Antique & Beautiful Firearms) has a short overview of some of Colonel Lewis’s lesser known designs. For example, many people know that it was Hitler’s naming of the MP. 44 “Sturmgewehr” that brought the term “assault rifle” into the popular consciousness, but did you know that one of the first uses of this term was by Colonel Lewis in describing his competitor to the Browning Automatic Rifle?
Lewis’s 1916 design for what he called his “assault phase rifle” weighed 13 pounds, compared to the BAR’s 16 pounds, was magazine-fed, with select-fire capability. When he demonstrated his prototype weapon, he announced, “My rifle is as accurate as any weapon our services now use. But, when switched to fully automatic firing the new Lewis gun will give one man the firepower of many men.”
Strange Guns includes a description of the Lewis “Shock Rifle” (“shock” referring not to the way the gun was to be used, but the way it worked) in their article:
At heart the design utilizes a modified type of gas-trap system, one where a portion of the gas released by the muzzle blast enters and fills (or otherwise produces force within) a large casing almost entirely encapsulating the barrel (rather than simply a small cavity). This gas, or hopefully as is described in the patent, a “shock-wave” is sent bouncing backward after crashing against the end of the barrel casing shroud, exerting pressure upon a tubular piston (in the above rifle patent drawing, part 13, with the pistol, 55) “in the form of an annular disc which is slidably mounted upon the barrel” and filling the gap between the barrel and outer “casing” or shroud wall. This barrel-mounted tube piston is connected to a traditional solid piston rod housed above the barrel, which acts upon the bolt in a more or less standard fashion.
US Patent 1430661 explains the benefit of this system in these terms: “An important distinction must be drawn at the outset between the present automatic… firearm operated by shocks or pressure impulses, and firearms operated by the direct pressure of the heated gases of discharge upon parts connected with the actuating mechanism of the firearm. In the improved firearm the hot gases of discharge do not necessarily come into direct contact with the actuating mechanism… and preferably are transmitted to said mechanism… through the medium of an intervening column of air. Thus said mechanism, or said parts, do not become highly heated by the gases and do not become fouled by deposits therefrom, enabling the firearm to be operated for more extended periods without cleaning, and preventing jamming or inefficient operation due to said fouling deposits.” In addition, the patents explain, recoil is reduced and the overall mechanism forces air over the barrel and internal mechanism while firing, helping to further cool the weapon.
The Lewis machine gun was one of the first light automatic weapons ever produced, preceded in production only by the Danish Madsen LMG. Even though the Lewis machine gun would leave a lot to be desired in the way of portable automatic fire (the French in particular felt the weapon didn’t meet their requirements – leading eventually to the CSRG 1915 Chauchat), it still paved the way for later portable automatic weapons, and directly led to both the German FG-42 paratroop machine rifle and the American M60 general purpose machine gun.
Lewis, though, wasn’t content to stay within the confines of his machine gun design, and he worked on several other weapons, one of which was a .45 ACP automatic pistol featuring the characteristic Lewis double-lobe receiver design!