The Remington 7188 was a variant of the M1100 pattern shotgun but produced for combat operations. Unlike the average sporting use shotgun, the 7188 was made to be full auto with a cyclic rate of 480 rounds a minute and was gas operated unlike the 11-48.
Production began around 1967 and the guns were sent to Vietnam where they were most famously used by the Navy SEALS. Several autobiographies mention the use of the 7188 and the user’s opinion on it. Like most people, it didn’t take long for the end users to stop being impressed with the amount of lead that could be slung compared to the amount of time it took to reload the shotgun once fired empty.
At least a few were fitted with the “duck bill spreader”, A type of muzzle device , or choke that dispersed the shot in a horizontal pattern rather than cone shaped from the muzzle. Reportedly the duck bill used with #4 buck was the magic combination to put a man down near instantly.
First developed specifically for use by US Navy SEALs in Vietnam, the first example of the Remington 7188, the Mk 1, appeared in 1967, and was perhaps the most destructive close combat weapon produced to that date. Developed from the Remington 1100, the Model 7188 was a fully-automatic version of that weapon, with some other modifications requested by the SEALs. Though these weapons were never large in number, the Mk 1 version was the most common of them; it had a perforated barrel shroud, extended tubular magazine, bayonet mount, and adjustable rifle sights. The Mk 2 was identical, but used a ventilated barrel rib and front bead sight of a standard shotgun. The Mk 3 was also identical to the Mk 1 but did not have the perforated barrel shroud. The Mk 4 was a Mk 3 with standard shotgun-style sights. The Mk 5 was also similar to the Mk 1, but did not have an extended magazine, and also did not have the perforated barrel shroud. The Mk 6 was identical to the Mk 5, but had standard shotgun-style sights.
While the SEALs liked the fantastic destructive power of the Model 7188 (especially with the custom loads they tended to use), they found the Model 7188 had one big problem: it was highly-sensitive to dirt and fouling, and this made it quite unsuited for general use in Vietnam. In addition, the enormous recoil of a full-auto burst (even at the low cyclic rate of the Model 7188) was difficult to control, and even with an extended magazine, the ammunition supply was thought to be too small by many SEALs. There were never more than a couple of dozen of each Mark of the Model 7188 made, and they were withdrawn from service within a few years, a weapon experiment that ultimately failed. Some were converted back to semiautomatic fire; though this essentially turned them back into Remington 1100s (albeit, with unique markings and an unusual selector lever), they were designated Model 7180s.
It had an extended magazine, perforated barrel shroud, bayonet mount and adjustable rifle sights. This is the most common version.
This was identical to the Mk 1, but had a ventilated barrel rib and front bead sights of a standard shotgun.
It was identical to the Mk 1, but lacked the perforated barrel shroud.
This was a Mk 3 with standard shotgun sights.
This was a Mk 1 with no perforated barrel ribs and lacked an extended magazine.
This was a Mk 5 with standard shotgun sights.
The shotgun has a lot of appeal to some people but the truth is it has very distinct and limited roles, even more so when in an environment like the jungles of Vietnam. Full auto shotgun even less useful. The 7188 was an interesting footnote in a time of “space age” advancement in weapons technology and theory. Of course some people never let any idea go to waste and so we see fullauto shotguns still coming out from time to time. Either way you come down on the shotgun as infantry weapon argument, I think we can all agree that a limited 8 round magazine with reload speed comparable to a Colt peacemaker is not something you would want to be stuck with if going against 20 people with AKs.