Entering the Vietnam War (1955-1975), the United States Navy SEALs (SEa, Air and Land) special forces employed all manner of weaponry for their various clandestine sorties in the region. The Teams utilized suppressed pistols, shotguns, experimental assault weapons and various submachine gun types when engaging enemies behind the frontlines. One weapon that found favor was the Swedish-originated Carol Gustav m/45 submachine gun line which promoted compactness, a proven man-stopping round and reliability in an otherwise unforgiving combat environment.
The m/45 was born during World War 2 (1939-1945) where Sweden managed to stay neutral during the conflict despite the invasions of Norway to its West and Finland to its East. Despite their neutrality, work was undertaken on several weapons of note including tanks and various small arms. The m/45 submachine gun, adopted in 1945, proved itself a highly-conventional submachine gun design utilizing a simple, straight blowback action while chambered for the widely available German 9x19mm Parabellum pistol cartridge firing from a 36-round detachable box magazine. Some 300,000 of the type were produced from 1945 to 1964 and additional stock emerged through local production in Egypt (as the "Port Said/Akaba") and Indonesia.
However, in 1966, Sweden halted its export of weapons to the United States in protest of the Vietnam War. This left the SEALs without a reliable stock of new m/45s and all-important spares, prompting famous American gunmaker Smith & Wesson to attempt a local copy based on the m/45 and sell this model to the US Navy. This work produced the local "M76" ("Model 76") which was made available by 1967. However, the US Navy held little interest in acquiring the weapon as the war had moved along, leaving the M76 as nothing more than a footnote in American firearms history. The limited batch of units that were produced between 1967 and 1975 eventually made up some of the US Navy stock and was procured by some US law enforcement branches and a few civilian owners. Clones of the weapon saw limited sale as the "M760" (under license by "MK Arms") and the "M76A1" (under gunmaker "Global Arms") for a time.
As in the Swedish design, the M76 was chambered for the 9x19mm Parabellum pistol cartridge and utilized a basic blowback action. It offered a rate-of-fire of 720 rounds per minute. Feeding could be by way of a 14-, 24- or 36-round detachable box magazine. Sighting was through a front and rear iron installation. The weapon weighed 7.25 when unloaded and a manageable 8.75lbs when loaded. Its overall length measured 30.5 inches though, with its hinged, foldable stock, it would be collapsed down to a handier 22.5 inches. Its barrel was just 8 inches long.
Its receiver was tubular in shape with a threaded, perforated heat shield over the barrel. The charging handle was set to the right side as was the ejection port, the latter fitted over the magazine well. The trigger was mated to the pistol grip handle at the rear and featured a large ring guard suitable for a gloved hand. The rear iron sight was set over the grip area while the forward sight was just forward of the ejection port along the receiver. The shoulder stock was a thin, wired frame design and hinged to fold over the left side of the receiver. Magazines were straight, detachable boxes and inserted into the awaiting well, doubling as a vertical forward grip.