PERSEVERANCE PAYS OFF


smokeless powder in 1884 was the first key. Smokeless propellants reduced the visible signature created when a weapon was fired, providing a significant advan- tage on the battlefield. Tey also enabled higher chamber pressures and greater projectile velocity, which in turn enabled the use of smaller diameter, lighter-weight projectiles with a greater effective range. Tese were enormous advantages that were recognized and exploited almost immediately. Rifles could be designed with shorter barrels, which meant lighter- weight weapons. Lighter projectiles meant that the individual Soldier could carry more ammunition. Additionally, the use of smokeless propellants greatly reduced the amount of corrosive residue left behind in the weapon from the burned propellant. With the dramatic reduction of corrosive fouling, it became possible to design reli- able mechanisms that could eliminate the requirement to manually manipulate a bolt to extract a spent cartridge, cock the weapon and load a fresh cartridge in the chamber. Weapon designers recognized the possibility, but combining the new technologies was another matter.


Tere were essentially two competing technologies:


1.Using the recoil energy to operate the action;


2.Using the energy of combustion gases to operate the action.


Recoil-operated mechanisms emerged first.


THE RECOIL APPROACH Semiautomatic pistols emerged in the late 19th century. For low-powered pistol cartridges, the inertia of a slide combined with the tension of a spring sufficed to keep the cartridge case in the chamber long enough to allow chamber pressure to fall off. Higher-powered cartridges required a breech-locking mechanism, and


a method of delaying breech unlocking. Te U.S. M1911 pistol used a short recoil design, in which recoil caused matching grooves and lugs in the barrel and slide to disengage after a relatively short length of travel caused by recoil.


Recoil-operated design of semiautomatic weapons was not confined to pistols. Te


COMPARATIVE QUALITY


The U.S. Marine Corps’ two primary rifles in WWII were the M1903 Springfield (middle) and the M1 Garand (bottom). A .30-40 “Krag” rifle is shown at top. (Photo by U.S. Marine Corps)


The desire to develop and field a self- loading infantry rifle was almost universal in the years between the first and second World Wars.


original Maxim machine gun, which first appeared in 1884, used a recoil-powered toggle lock linkage in its design.


During World War I, the U.S. developed the Pederson device, a recoil-powered adapter that could be placed in a slightly modified M1903 Springfield rifle, making it capable of semiautomatic fire. However, the Pederson device did not use the .30-06 rifle round. Instead, it employed a much lower velocity pistol-type cartridge, so it lacked the range and power of the full- sized rifle round. Te technology to adapt semiautomatic operation to a full-power individual infantry weapon just wasn’t available.


EXPANDING GAS Te competing technology used expanding combustion gases to cycle the operating system. Inventors tried a variety of tech- nological approaches to use propellant combustion gases to achieve automatic or


98


Army AL&T Magazine


Fall 2021


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