Shotguns have been used in America's wars since the revolution, only then they were called "fowling pieces." Early units of Confederate cavalry were armed with shotguns and some remained in service until the end of the War Between the States.
A Joint Service Combat Shotgun Program report on the lethality of shotguns in war states, in support of the use of the shotgun in warfare, "the probability of hitting a man-sized target with a shotgun was superior to that of all other weapons", and goes on to support this with statistics compiled by the British from the conflict in Borneo in the 1960s.
The buckshot typically used in a combat shotgun spreads out to a greater or lesser degree depending on the barrel choke, and can be effective at ranges as far as 70 m (75 yards). The delivery of the large number of projectiles simultaneously makes the shotgun the most effective short range weapon commonly used, with a hit probability 45% greater than a submachine gun, and twice as great as an assault rifle. While each pellet is only as effective as a small caliber handgun, and offers very poor penetration against an armored target, the multiple projectiles increases the likelihood of one or more peripheral wounds.
A number of compromises are involved in choosing a shot size:
* Smaller pellets lose velocity more rapidly and penetrate the target less
* Larger pellets means fewer pellets, resulting in a reduced probability of hits
* Heavier loads produce more recoil and less velocity than lighter loads
* Reduced recoil loads (less shot and/or lower velocity) may produce smaller patterns, which may decrease hit probability, -- Wikipedia.
Marine in the Pacific armed with 12 Gauge shotgun.
They were used in both world wars, in Korea and in Vietnam.
They continue in service today, especially popular for breaching doors.
A Mossberg 590 being used by a US Marine for door breaching in Karma, Iraq, in 2005.
They have always been the guerrilla's "butter knife gun" of necessity:
Due to the widespread use of the shotgun as a sporting firearm, it is used in guerilla warfare and other forms of asymmetric warfare. Che Guevara, in his 1961 book Guerrilla Warfare, notes that shotgun ammunition can be obtained by guerrillas even in times of war, and that shotguns loaded with heavy shot are highly effective against unarmored troop transport vehicles. He recommends that suburban guerrilla bands should be armed with easily concealable weapons, such as handguns and a sawed-off shotgun or carbine. Guevara also mentions an improvised weapon developed by guerrillas consisting of a sawed-off 16 gauge shotgun provided with a bipod to hold the barrel at a 45 degree angle. Called the "M-16", this was loaded with a blank cartridge formed by removing the shot from a standard shotshell. A wooden rod was then placed in the barrel, with a Molotov cocktail attached to the front. This formed an improvised mortar capable of firing the incendiary device accurately out to a range of 100 meters. -- Wikipedia.
While I have seen an inert grenade projected off of a twelve gauge using the Guevara method, I don't think I'd want to try that molotov cocktail thing. I used to work in a burn unit for a mercifully short period of time in the '70s.
But since shotguns are so ubiquitous, it makes sense to try to maximize their capabilities. In the 90s, I tried to popularize flechette rounds for 12 gauge "jack booted thug door greeter" purposes, the theory being that tungsten-steel flechettes could penetrate the ATF raid party vests then in use.
A reader, in response to my post on flash-bangs yesterday, forwarded a link to what he called "the poor man's flash-bang," which got me thinking again on the whole combat shotgun theme.
This is the ALS Technologies 1208 "Bore Thunder (Muzzle Bang)."
ALS bills this as a "low cost highly effective device (which) produces a stun/diversion effect by using a flash with an extremely powerful concussion blast from a 12 gauge shotgun muzzle."
ALS makes a number of useful cartridges for the twelve gauge, including the ALS1209
Aerial Pest Control (Delayed Bang). This is what is lnown in the vernacular as a "bird bomb." The ALS product description: "This low cost highly effective device produces a diversion effect by using German engineered pyrotechnics 75-200 feet from firing point. . . The Aerial Pest Control was developed as a diversion, animal control and personnel control device for use in a variety of applications."
The ALS 1209 "bird bomb."
Also made by ALS, the ALS1210S Door Breaching Cartridge.
Ever since the advent of modern 12 Gauge cartridges loaded with deer slugs, cops have been blowing the hinges off of doors with them. Modern door breaching rounds are designed to blow off the hinge but dissipate their projectile so innocents within the room are not hurt.
From the ALS product description:
This low cost, highly effective device is a frangible projectile made of powdered copper and tin pressed into a single projectile. The door breaching cartridge produces an effective means of removing locks and hinges from metal or wooden doors constructed of materials up to 16 gauge steel. Limited projection of hazardous debris and collateral damage on the opposite side of the door is minimized. . . The Door Breacher was developed to provide an alternative to the battering ram and limit exposure to shots fired from within areas upon entry.
The combat shotgun remains a useful tool of war. There are tens upon tens of millions of shotguns in the hands of the armed citizenry. It only makes sense to use what you have and optimize performance by using specialty ammunition.