FG 42 The FG 42 ( German : " Fallschirmjägergewehr " 42 or " paratrooper rifle 42 " ) was a selective fire battle rifle produced in Nazi Germany during World War II . The weapon was developed specifically for the use with Fallschirmjäger airborne infantry in 1942 and was used in very limited numbers until the end of the war . It combined the characteristics and firepower of a light machine gun in a lightweight form no larger than the standard - issue Kar 98k bolt - action rifle . Considered one of the most advanced weapon designs of World War II , the FG 42 influenced post - war small arms development and ultimately helped to shape the modern assault rifle concept . History . At the time of the Battle of Crete ( Operation Mercury ) , German " Fallschirmjäger " were equipped with the same assortment of small arms as the " Heer " , carrying only pistol s and hand grenade s on them during airborne jumps , with submachine gun s , rifle s and crew - served weapons stored separately in containers that were dropped from the wing of the exit craft . The German parachute harness , with a single strap attached to the body making the paratrooper land on his hands and knees in a forward roll , did not allow for heavier equipment such as rifles and machine gun s to be safely carried during jumps . At Crete , long - range rifle and machine gun fire from dug - in Commonwealth defenders inflicted heavy casualties upon the outgunned German paratroopers in the early stages of battle as they attempted to retrieve their support weapons from containers scattered all over the battlefield . These combat experiences demonstrated the need for a rifle that could be carried on the person of the paratrooper . Development . In 1941 , the German Air Force ( " Luftwaffe " ) , requested a selective fire hand - held weapon for the paratroopers ; Senior Staff Air Secretary Ossenbach at the " GL / C Erprobungsstelle - 6 " ( GL / C E - 6 — the " Luftwaffe " Weapons Development Branch at Tarnewitz near Lübeck ) was approached informally to develop this special new weapon . The Reich Air Ministry ( " Reichsluftfahrtministerium " or RLM ) sought to develop a universal shoulder - fired automatic rifle that could replace the bolt - action rifle , submachine gun , and light machine gun in the air assault role . The proposed weapon would also simplify logistics and provide greater firepower to the individual paratrooper . The RLM attempted to initiate a formal weapons development program through the " Heereswaffenamt " ( the HWaA , or Army Ordnance Department ) — responsible for German small arms development — but conflicting priorities and friction with the Army ( the HWaA dismissed the undertaking as unrealistic and offered their G 41 ( W ) semi - automatic rifle instead ) led to an independent development by the " Luftwaffe " . Plans were laid out to form a central authority for the new program at the " Luftwaffe " testing station at Tarnewitz . The engineers on staff had acquired considerable expertise developing lightweight automatic weapons , having successfully converted the MG 15 aircraft machine gun to a ground configuration . However , due to the high casualties sustained by the paratroopers during Operation Mercury , Hitler changed his mind about the usefulness of airborne assaults and the plans were terminated . Nevertheless , " Luftwaffe " " Reichsmarschall " Hermann Göring privately ordered the continuation of the project . The RLM went directly to German industry with its plans — the so - called LC - 6 specification issued 14 December 1941 mentioned amongst others that the weapon should not exceed in length , should not be significantly heavier than the Kar 98k rifle , should be able to fire single shots from a closed bolt , provide fully automatic fire from an open bolt , feed from detachable 10 or 20 - round magazines and be able to fire rifle grenade s . Despite the introduction of the intermediate 7 . 9mm " Kurz " cartridge promoted by the " Heer " ( developed for the promising MP 43 assault rifle ) , the " Luftwaffe " favored the long - range potential of the standard 7 . 92×57mm Mauser rifle round and this caliber was one of the main design prerequisites . Prototypes . Six manufacturers were solicited for prototype designs : Gustloff - Werke , Mauser , Johannes Großfuß Metall - und Lackierwarenfabrik , C . G . Hänel , Rheinmetall - Borsig and Heinrich Krieghoff Waffenfabrik . Several contracts were awarded but only a few prototypes are known to have been submitted . Mauser offered a version of the MG 81 ( rejected due to excessive weight and its belt - fed operation ) while Krieghoff presented a rising - block prototype , which too was quickly dropped . A design credited to Rheinmetall - Borsig ' s Louis Stange of Sömmerda proved satisfactory and underwent military trials conducted by the GL / C E - 6 test station at Tarnewitz in mid - 1942 . This early prototype , known under the factory designation Gerät " 450 ( " device 450 " ) or Ausführung " " A " ( " type A " ) , was intended to be a pure sheet metal design , using pressed steel in the construction of the receiver , buttstock and corrugated handguard . The proposed system of operation was modeled on that used in the World War I Lewis light machine gun , with a gas - operated turning bolt action geared to a spiral ( clock - type ) recoil spring . The type " A " was never produced beyond model form , but the basic design layout was retained for further development . With the basic characteristics of the LC - 6 accepted , a series of modifications followed . The revised " Ausführung " " B " replaced the sheet metal handguard with a resin - impregnated fiber type that provided protection against heat and a better grip when wet . These tests exposed several shortcomings , addressed by Stange in April 1942 with the LC - 6 / II prototype . The prototype was then submitted to a series of endurance tests led by the HWA and further modified to increase functional reliability and durability , resulting in the final LC - 6 / III prototype variant that was ultimately accepted into production as the FG 42 . Fifty rifles were fabricated by Rheinmetall - Borsig for evaluation purposes by the end of 1942 . A pre - series batch of 50 rifles was produced in early 1943 and 6 examples were sent to GL / C E - 6 for additional testing . Almost identical to the LC - 6 / III , these guns differ from later models by using a smooth sheet metal buttstock and an experimental muzzle brake . The weapons experienced serious malfunctions : one rifle suffered a catastrophic failure after firing only 2 , 100 rounds , a soldier was injured when attempting to fire a rifle grenade and the pressed metal buttstock would deform after launching a small number of rifle grenades . Production . Several other improvements were made before being authorized for large - scale production . The original Rheinmetall design used chrome - nickel steel heavily in many essential components , a strategic alloy in short supply . When the " Luftwaffe " was finally given permission to produce 3 , 000 rifles for combat trials , the material specifications were changed to accommodate the use of manganese steel as a substitute . The Heinrich Krieghoff company of Suhl ( authors of the previous unsuccessful LC - 6 tender ) was contracted to manufacture the FG 42 in limited quantity as Rheinmetall did not have the capacity to bring the FG 42 into serial production . The weapon was first used by German paratrooper commando s during the Gran Sasso raid in 1943 ( the rescue of Benito Mussolini ) . The weapon system underwent continuous development . Its expedited development , remedial changes to the original design and ever - changing " Luftwaffe " requirements resulted in a myriad of variants . Post - war literature typically identifies three versions , however the Germans did not give them separate designations ; the " Model I " , " Model II " and " Model III " were never officially referenced and period documents simply refer the weapon as the " FG 42 " , and the reference was always made to the latest production model . Design details . General configuration / layout . The FG 42 was a select - fire air - cooled weapon and one of the first to incorporate the " straight - line " recoil configuration . This layout , combined with the side magazine , placed both the center of gravity and the position of the shoulder stock nearly in line with the longitudinal axis of the bore , a feature increasing controllability during burst or automatic fire . The operating system was derived from that used in the successful Lewis light machine gun with a gas piston - actuated turning bolt locking mechanism . This system used pressurized exhaust gases from the bore and channeled them through a port drilled in the barrel into a gas cylinder located under the barrel . The rapid build - up of propellant gases imparted rearward pressure on a long - stroke piston , driving it backwards , while an extension of the bolt carrier interacted with a helical camming slot machined into the bolt carrier , converting this linear movement into an angular velocity and forcing the bolt into a rotary motion , clearing the locking juts and unlocking it near the end of the bolt carrier ' s travel . The weapon was locked into battery by two lugs on the bolt head which recessed into appropriate cavities machined into the receiver walls . Owing to its main intended use by paratroopers , the rear sight ( which necessarily was rather high due to the straight stock design ) was a flip - up construction . Receiver specifics and magazine feeding . The receiver was a sophisticated , machined alloy forging with the magazine housing placed on the left - hand side and the ejection port on the right . The seemingly awkward placement of the magazine housing ( horizontally to the side rather than directly beneath the receiver ) allowed the bolt mechanism to extend into the buttstock assembly , effectively reducing the overall length of the weapon as the magazine well did not interfere with the location of the pistol grip . The pistol grip was integrated into the trigger group assembly , a separate housing containing the trigger mechanism and fire control components , and was formed from pressed sheet metal during fabrication from two separate halves and then welded together . The rifle fed from either a 10 or 20 - round detachable box magazine . Firing . The FG 42 fired in semi - automatic mode from a closed bolt , accomplished by delaying the release of the firing pin ( mounted on the bolt carrier and released by the front sear notch ) until after the trigger had been pressed ; the short lock time , and little movement in the action during firing translated into greater single - shot accuracy . When operating in the automatic mode , the sear mechanism was designed to fire from an open bolt by simultaneously releasing both the bolt and bolt carrier . This had the advantage of preventing a phenomenon known as " cook off " where the heat of repeated rounds being fired caused a chambered round to overheat and prematurely ignite the powder or primer . With automatic fire selected , the bolt would remain open between bursts to provide maximum cooling . The rotating fire selector switch was situated in the trigger group , above the pistol grip on the right side . The change lever also served as the safety , disabling the sear mechanism when engaged . Testing . The FG 42 was intended to fill a key niche in Nazi Germany ' s arsenal and was produced only in small numbers . It was somewhat well received by paratroopers when tested , but it did have its drawbacks . The FG 42 had a 20 , or sometimes 10 , round magazine that was mounted on the left side of the rifle . Though a side - mounted magazine was common in submachine guns , the larger magazine with heavier ammunition of a full - powered rifle tended to unbalance the weapon . In addition , muzzle rise with automatic fire was substantial and controllable bursts were difficult . This made full - automatic fire only marginally useful . The FG 42 used a fairly sophisticated muzzle device that did help with recoil and muzzle flash , but made blast and noise much greater than on other similar weapons . The US M14 rifle had similar problems and attempts were made to upgrade that rifle the same way with an in - line stock and muzzle device . Influences / derivatives . Some features , such as the details of the gas - operated bolt selection process , were studied by US Army engineers after the war . These , along with some aspects of the MG42 , are commonly reported to have been incorporated in the similarly troubled M60 . The American M41 Johnson LMG has many parallels with the contemporary FG 42 . Both had in - line stocks , fed from the left side , and both fired from the open bolt in automatic mode and closed bolt in semi - automatic mode . Despite these similarities , there is no evidence that either weapon had any effect on the design of the other . As they were both seeking to solve similar problems , it is reasonable to expect that each weapon ' s respective engineers approached these problems similarly but independently , unaware of the developments of their counterparts . Last known derivatives of the FG 42 were the Sturmgewehr 52 and M60 machine gun . Deployment . After approximately 2 , 000 FG 42s had been produced by Krieghoff , supplies of the manganese steel from which the receivers were forged were diverted to other needs ; this meant a redesign was required to use stamped sheet metal in its place . Field reports were also requesting minor improvements , such as : relocating the bipod from the front of the handguard to the muzzle to reduce shot dispersion ; changing the pistol grip angle to near vertical ; enlarging the handguard and changing the stock from stamped steel to wood to minimize overheating . These changes , particularly the pistol grip change and the bipod relocation , are clearly visible on late - model FG 42s . Both models also had a simple flip - out spike bayonet under the barrel hidden by the bipod . In the later version the bayonet was shortened from around to around .