Special Operations Weapon

The Special Operations Weapon was a shotgun used by US Navy SEALs in the Vietnam War.^[1] It was designed by Carroll Childers, an engineer at the Naval Special Weapons Center.^[2] The 870 mod kit provided SEAL shotgunners with a magazine that holds 20 rounds.^[3] The SOW is full-auto.^[4]

Combat scatterguns

The scattergun is known for its ability to be ruthless. It has been in U.S. military service since trench warfare began in World War I. Marine combat in World War II proved the utility of the military shotgun for close-range encounters. It was also deployed with Navy SEALs to Vietnam. The Ithaca Model 37 was standard issue in the Navy during the 1960s, used mostly by boarding parties and for inport ship security. The SEAL Teams first go the guns, they stripped off the barrel shroud and the bayonet lug. The downward ejection of the gun gave it a further advantage over competing designs. It was particularly difficult to jam. With practice, the SEALs could achieve an immediate return fire. The gun's limited ammo capacity was a problem though. By the end of 1967 a modification kit was designed that extended the gun’s magazine to hold three additional rounds.

Box magazines

The Ithaca’s was very difficult to reload. A detachable magazine was designed early in 1970s. A pair of aluminum boxes could feed 10 or 20 rounds, arranged in two rows to be compact. The Navy’s standard issue Ithaca loaded and ejected from the same hole under the receiver, it was not the ideal conversion to the new magazine feed. The Remington 870 was mechanically suited, already in the Marine Corps inventory, and well received by Force Recon units that operated with SEALs. A simple and easily applied modification kit for the 870 performed well in testing and was set for production when the U.S. was pulling out of Vietnam.

Pellets and chokes

Another characteristic needing improvement was in patterning, the distribution of multiple lead balls at varying distances from the muzzle. There are at least two main components to this—pellets and chokes—and the ideal combination sparks a never-ending debate among shotgunners. While the big double-ought round with its nine .33 caliber balls remains even today a combat-proven military standard, it is noted in contemporary accounts that most SEAL shotgunners preferred smaller #4 buckshot. Perhaps puzzling to the casual student of wound ballistics, this should not be hard to understand when properly considered. Although the projectiles in the #4 round are only .24 caliber, their combined weight in the shell is the same as that of the nine pellet 00 buckshot, and there are 27 of them flying though the air instead of nine. Keeping in mind that the incapacitating effect of gunshots increases markedly with multiple hits, the #4 shot is still large and heavy enough so that relatively few need to find the mark to cause sufficient damage to immobilize or kill. This plethora of flying lead would be of only marginal utility if not efficiently delivered to the central mass of a man-sized target at realistic combat ranges, and this is where chokes come in. Any number of chokes—most simply defined as muzzle diameter restrictors—have been developed over the decades for sporting and military applications. But the SEALs wanted something quite different. Give us something, they asked, that will increase hit probability and thus pointman survival in a close-range jungle ambush. Initial experiments at Frankford Arsenal in the mid-1960s pointed to ordnance engineer Charles Greenwood’s duckbill choke as a promising avenue for further development. When properly oriented on the muzzle, this V-shaped device restricts the top and bottom of the shot pattern so that a larger number of pellets fly in a horizontal plane, increasing hit probability against closely grouped enemies or those running parallel to the gunner. However, SEAL combat experience with duckbill-equipped Model 37s and carefully observed formal testing would eventually demonstrate that the concept was not as practical as hoped except at relatively close range. According to Swearengen, controlled tests showed the duckbill would consistently put only a few pellets from a #4 shot anywhere in a man-sized target placed 40 meters away. In contrast, a traditional cylinder choke could be counted on to deliver on target at least 60 percent of the balls; that is 16 hits per shot. This pattern density is all the more crucial when shooting through dense jungle vegetation, and the duckbill’s popularity faded away along with its novelty value.

Full auto follies

As good as the Model 37 became—and the box magazine–modified 870 could have been—the ageless concept of “more is better” spurred other areas of experimentation with a series of noteworthy developments in rapid-fire shot throwers. The Remington 7188, first to be fielded by the SEALs, was a full-auto jackhammer based on this great American gunmaker’s respected Model 1100 semiauto hunting gun. Although boasting a cyclic rate of about seven rounds per second, the gas-operated 7188 reportedly was difficult to control as well as prone to malfunction from environmental factors. Meanwhile, back at the Naval Surface Warfare Center in Dahlgren, Va., magazine master, gun enthusiast and engineer Carroll Childers had been hard at work on a completely different full-auto shotgun. Colorfully acronymed SOW for Special Operations Weapon, it was to be no mere conversion of an existing gun. Childers knew he had to come up with something completely different to meet the demanding standards of Marine Force Recon and Navy SEALs. Most importantly, the gun would have to be a light and compact package that would reliably feed and controllably fire not only various military standard 12-gauge shells, but also to launch a new family of special-purpose munitions. Although of the same caliber, these SPMs had necessarily longer cases and widely varying recoil impulses. A developmental SOW—called at the time the MIWS for Multipurpose Individual Weapon System—is preserved among many other one-of-a-kind artifacts in the Naval Historical Center’s collection. The chunky and stubby slab-sided aluminum and steel first-generation prototype is fed from the top using one of the multi-round box mags Childers developed for the 870 shotgun. This one is apparently intended for hip fire only, featuring two pistol grips with heavily worn and deeply scratched olive drab paint giving much evidence of rough use during its short, but fascinating life as a test subject. Development of the Childers SOW and its remarkable family of 12-gauge ammo had come tantalizingly close to warranting a full-scale program when the Pentagon pulled the plug on small arms research and development.

See also

• List of shotguns

References

US patent 3736839 

External links

• "Firearms secret projects" thread at Secret Projects Forum