Blowback is a term used in espionage to describe unintended consequences. In context, it can also mean retaliation as the result of actions undertaken by nations. The phrase is believed to have been coined by the CIA.
In the 1980s, blowback became a central focus of the debate over the Reagan Doctrine, which advocated militarily supporting resistance movements opposing Soviet-supported, communist governments. Critics of the Reagan Doctrine argued that blowback was unavoidable, and that, through the doctrine, the United States was inflaming Third World wars. Conservative advocates, principally at the conservative Heritage Foundation, responded that support for anti-communist resistance movements would lead to a "correlation of forces," which would topple communist regimes without significant retaliatory consequence to the United States, while simultaneously altering the global balance of power in the Cold War.
Given prior CIA support of the Islamic insurgency in Afghanistan and purportedly also of Osama bin Laden, it could be argued that the September 11, 2001 Terrorist Attack is the most prominent contemporary example of blowback, since some contend that this U.S. support actually helped build Bin Laden as a geopolitical force.
- Blowback: The Costs and Consequences of American Empire, by Chalmers Johnson, ISBN 0805062394
In a blowback system the expanding gases from the round being fired "blow back" the breech of the gun, which is left unlocked. This system is only really useful for smaller weapons with short barrels, where the breech can start moving as soon as the round is fired. With larger weapons the breech would move too far before the round left the barrel, and can spoil the aim. Thus blowback is typically found only on pistols and submachine guns.
The cyclic firing rate is usually very high, because the mass of the bolt determines how quickly the action operates. Users prefer light-weight weapons, and this causes the gun to cycle quickly. In a blowback firearm, the firing pin is often just a small projection on the bolt. When bolt slams home, the round fires. These guns usually stop with an open chamber. They are also rather unsafe, because a hard bump can cause the heavy bolt to spring the sear. The sear releases the bolt, and then the gun may fire.
Blowback also refers to firearms that blowback dust, expended, and infrequently minor debris upon firing, often being caused by lose seals or the recoil and short barrels of pistols. This is often called Pistol Blowback. This can cause great irritation to eyes and in the rare case of debris, can actually cause scarring. Many ranges or organizations suggest the use of, or require safety glasses when firing pistols.