Ian McCollum has a Forgotten Weapons video up on a the S&W M-76 9mm submachine gun. The M-76 is a close copy of the Swedish K that was used by Navy SEALs and other special forces in the Vietnam War. They had to go to S&W for a copy of the Swedish K after the Swedish Government refused to sell any more to the US military due to their objection to the Vietnam War.
I have been fortunate enough to have fired one of these submachine guns and I really liked it. Years ago, LuckyGunner ammo put on a blogger shoot in East Tennessee and this was one of the full-auto firearms available to shoot. I found it easy to handle and quite a fun way to waste ammo. If I ever decide to take the full-auto plunge, it is one of the firearms on my semi-affordable buy list.
Ian included this in his description of the M-76:
Early in the Vietnam War, the US Navy acquired a quantity of Swedish M/45B submachine guns (“Swedish K”) for special forces use. By 1966, however, the Swedish government would no longer authorize sales of arms to the United States because of involvement in the Vietnam War. So instead, the US turned to Smith & Wesson to design and produce a copy of the gun. In January of 1967 the first prototypes were presented of the S&W Model 76, which incorporated a number of changes form the Swedish original. The S&W gun had an ambidextrous selector lever allowing either semiauto or full auto fire, and a permanently fitted magazine well for use with a close copy of the Suomi 36 round double stack box magazine. Most interestingly, the inside of the receiver tube is cut with long rifling-like grooves to allow dirt and fouling to accumulate without impacting the gun’s reliability.
Only a relatively small number of 76s were procured by the Navy (under the designation Mk 24 Mod 0), as the availablity of AR15/M16 carbines proved more attractive option than 9mm submachine guns. The company would continue making them until 1974, with a total of 6,000 produced. This particular example is a T prefix serial, which I suspect (but cannot prove) was Navy purchase.
The reputation of the S&W 76 has been unfortunately tarnished by a succession of full auto and semiauto clones, none of which are as well made or as reliable in use as the original S&W production.
The M-76 that Ian is showing in the video is up for auction by Morphy Auctions. Checking the latest auction bid, it would take you at least $4,000 plus the 26% and the $200 tax stamp to take this home. Still when you consider that no new NFA machine guns are coming on to the market that you can buy (thank you, Hughes Amendment), this is a quite reasonable price.