The Fallschirmjagergewehr 42 (FG42) was developed specifically for the lightly armed and mobile German paratrooper element around the full-sized 7.92x57mm Mauser cartridge. As a military small arm, the type was of excellent quality and reliable performance, suffering only from internal opposition, changes to German airborne tactics and expensive engineering which led to fewer than 9,000 units being produced. Its imprint on modern assault rifle design was undisputed, however, for several of her characteristics were studied at great length in the years following the war - particularly her compact and lightweight action and gas operation. The "straight line" design approach was heavily adopted and still witnessed in modern designs leading to the FG42's unofficial title of "excellent failure".
When the Germany Army adopted the StG44 select-fire assault rifle centered around the new 7.92x33mm "kurz" short cartridge, the leadership of German paratroop elements of the Luftwaffe were compelled to follow suit - lacking any sort of viable long range automatic weapon. Instead of following the Army lead, however, they instead looked to an all-new design built with the paratrooper in mind - these battlefield units always forced to be lightly armed yet dropped into the thick of combat situations. German airborne experiences during the invasion of Crete dictated that the short cartridge of the new StG44 was lacking in the long range hitting power required, particularly when compared to the ranged success of British troops firing on the Germans with their full-power rifle cartridges. As such, it was decided that the new weapon would be centered around the full-sized 7.92x57mm cartridge which would be readily available on all fronts that the German military operated on. The design would have to yield the same select-fire flexibility of the StG44 and provide machine gun-type automatic firepower yet arrive in a compact form suitable for airborne units. With the blessing of Hermann Goering himself, the parachute arm of the Luftwaffe was granted their weapon. In late 1940, Rheinmetall-Borsig AG was charged with its design and development though, because of the competitive nature of the various branches of service and all such small arms traversing through the Army, authorities submitted their request for the new weapon through the Luftwaffe in an attempt to bypass expected opposition.
Rheinmetall-Borsig unveiled their working prototype in the middle of 1942 for formal evaluations. The weapon proved a decidedly unique concept developed along a "straight line" design approach - all of the major components - buttstock, receiver and barrel - were situated in line with one another, an arrangement largely adopted in modern assault weapons of today. Weighing at a manageable 10lbs, the FG42 resembled a mix of service rifle and machine gun which, considering its self-loading, selective fire automatic action, was essentially a highly portable light machine gun with qualities akin to a modern day assault rifle. In any case, the weapon could prove valuable for those lightly-armed paratroopers.
The action was contained in a compact-as-possible housing to promote high portability. The overall design was of a largely elongated tubular form with a full steel "fish tail" style shoulder stock, a receiver housing the required internals, a shrouded slotted section serving as the handguard and a short length of exposed barrel. The barrel was completed with a "pepper pot" style muzzle compensator for recoil and featured an integral bayonet fitted under the barrel for close quarters combat. A folding bipod was affixed under the forward bulk of the frame for when the weapon was used in the light machine gun sustained fire role - even with the bayonet in place. In an awkward move, the detachable straight box magazine, containing 20 rounds of 7.92mm ammunition, was inserted into the left side of the receiver while spent shell casings ejected out of a port along the right. The action was initially manually cocked via an assembly along the right side of the receiver whilst sighting was through a forward and rear iron arrangement. One of the more peculiar design initiatives of the weapon became its heavily slanted pistol grip which angled rearwards, intended as an ergonomic gesture and one to lessen the chances of snagging on clothing and equipment during airdrops. The operation was cycled via a gas-actuated piston action with a turning bolt allowing a rate of fire of 800 rounds per minute. A fire selector allowed for single (from a closed bolt) and full automatic fire (from an open bolt to avoid "cook offs" in the chamber). Overall length was 36.9 inches with an unloaded weight of 9lbs, 10 ounces. The barrel measured 20 inches and muzzle velocity of the 7.92mm bullet was rated at 2,400 feet per second.
The Rheinmetall-Borsig design was formally adopted into Luftwaffe service as the "Fallschirmjagergewehr 42", abbreviated as "FG42" and sometimes recognized as "FjG42"). By this time, Germany was at war across multiple fronts and its conventional use of airborne troops had changed considerably since the costly Crete operation. Additionally, production facilities were ultimately under the influence of the German Army and little effort was done to ensure the FG42 was available in proper numbers, let alone fully developed in the field. Add to this the fact that, as was the case with other weapons of select German engineering, the FG42 was a complicated and expensive system to produce in the numbers required - death knells for any weapon during wartime. Production of the FG42 was undertaken regardless, though ultimate figures proved extremely limited - perhaps as little as 7,000 or as many as 9,000 units were produced before the end of the war in 1945.
In practice, the weapon was well-received by its few users and, as a small arm, it was of excellent quality and reliability. If the design held any limitations, it was primarily the side-mounted magazine which held the propensity to snag in the heat of battle and its awkward positioning about the frame made for an unbalanced weapon when under full automatic fire. The use of the full-power, full sized 7.92mm cartridge also made for a difficult weapon to aim with any level of accuracy when under full automatic fire. The magazine only held 20 rounds which limited the long term tactical usefulness of the weapon as a sustained fire system. The bipod proved too light in its construction and prone to bending in the heat of battle. Add to all this the haste in which the FG42 was shipped and various teething issues soon arose that were never entirely ironed out.
Regardless, the Luftwaffe took on initial stocks of FG42s wholeheartedly and, within short order, requested greater numbers. Its first notable use came in September 1943 during the successful commando-style raid by German paratroopers to rescue former Italian dictator Benito Mussolini. Aside from this brazen exploit, the German paratrooper had seen his days in World War 2 for they were increasingly utilized as traditional infantry into 1945.
Heinrich Krieghoff Waffenfabrik was eventually brought into the fold to increase production levels. An effort was undertaken to simplify the original FG42 design by enacting several key changes. The steel "fish tail" buttstock was dropped in favor of an all-wooden form of more conventional (and simpler) shape. A plastic or laminated wood handguard replaced the original perforated metal heat shields then in sue while the "pepper-pot" muzzle attachment was substituted with a finned slotted design. The bipod was relocated to the muzzle away from the frame and, perhaps the most notable of the changes, the angled pistol grip was replaced by a more vertical, "relaxed" design.
The revised FG42 brought about a slightly longer overall design at 41.7 inches, the barrel now measuring 20.6 inches in length. Cyclic rate-of-fire dropped to 750 rounds per minute while the 2,400 feet per second muzzle velocity of the 7.92mm bullet was retained.
Despite the measures to make the FG42 a more production-friendly weapon, the initiative failed to achieve the desired goal of elevated manufacture numbers. Between the two designs, it is estimated that the original FG42 was produced in 2,000 examples with the revised FG42 appearing in some 7,000 examples by war's end. The type was encountered in greater numbers in the West Front which led many observers there to erroneously believe that the FG42 was in wide scale service at the time. Stocks of the weapon ultimately fell to these advancing Allied forces from 1944 onwards and the truth of its limited reach soon unfolded.