Semi-automatic pistol

From Academic Kids

A semi-automatic pistol is a handgun commonly used as a sidearm by police and military all over the world. It is often referred to as a mere pistol, although that term encompasses several other types of small firearm as well. Most types rely on a magazine which feeds ammunition through the hollow hand grip into the chamber. This allows for short reload times and a larger number of rounds per loading than a revolver, at the cost of a more complex design and mechanism which is more prone to malfunctioning.



A semi-automatic pistol reloads the chamber with a new round automatically once the weapon is fired, without additional action by the user. This is accomplished by recoil operation. A semi-automatic will fire only one shot per trigger pull, as opposed to a "fully automatic" which continues to fire as long as the trigger is engaged or until all rounds have been fired. While both types of weapons operate on the same principles, fully automatic weapons must be built more ruggedly to accommodate the heat and shock caused by rapid firing, and it can be difficult to turn one action into the other type. A selective fire action can be converted back and forth with a simple flick of a switch, and often includes burst mode.

Semi-automatic pistols can be divided into "blowback" and "breechlock" pistols according to their principle of operation. In blowback pistols, the barrel is fixed to the frame and the breechblock, in its foremost position, is held against the barrel only by the force of the recoil spring. In breechlock pistols, the barrel is locked to the breechblock and recoils a short distance with it until it is unlocked, after which the breechblock and slide continues backward without the barrel. Blowback pistols are simpler to make and thus cheaper to make, but the blowback mechanism can only practically be used with cartridges of relatively low power.

Another differing point among pistols are their trigger and ignition systems. Early designs use so-called "single action" systems, where a hammer needs to be manually cocked to fire the first shot (though for subsequent shots the hammer is cocked by the energy associated with the recoil from the preceding shot). When the trigger would be pulled, the hammer would hit the firing pin which would then strike the primer of the round in the chamber and fire the pistol. For carry the hammer would simply be blocked in its cocked position with a manual safety. These early designs could not prevent the pistol from firing if dropped on a hard surface, as the firing pin was only being held in place by a spring. There was also a (very rare) risk that such a pistol would fire in fully automatic mode if the spring retaining the firing pin would become too weak with use. In that case the pistol would start firing and only stop when it would run out of ammunition, posing a great risk for its user.

Later designs introduced the "double action" system, which eliminated the need to first manually cock the hammer to fire. Instead, the hammer is cocked as the trigger is pulled. This first trigger pull in double action mode (uncocked hammer) is heavier than when in single action mode. After the first shot the pistol reverts to single action mode because the rearward motion of the slide (which cycles the pistol) cocks the hammer; the trigger pull weight in single action mode is usually half of what it is in double action mode. If the particular pistol has a manual safety, when it is engaged it will usually (depending on the design) decock the hammer and it will return to double action mode. There are also "double action only" designs in which there is no single action mode, as the hammer cannot stay in a cocked position. In most double action designs the trigger will be disconnected while the safety is applied. Note that some double action pistols lack the firing pin safety.

The newest designs use so-called striker systems, also called "safe action" or "semi-double action", in which there is no hammer and when one pulls the trigger one fully cocks the striker until it releases and fires the pistol. When the trigger is in ready position, the striker is blocked so that the pistol can not fire if dropped.


After Hiram Maxim introduced his recoil-powered machine gun in 1883, several gunsmiths set out to apply the same principle to handguns. The first model to gain any commercial success was the Borchardt self-loading pistol, designed by Hugo Borchardt and appeared in 1894. It featured a rather clever locking mechanism modelled after the human knee joint and proved mechanically reliable, but too large and bulky to be used comfortably by one hand. Equipped with a screw-on wooden stock it served well as small carbine, however. In 1896 Paul Mauser introduced his first model of the famous Mauser pistol. Using the powerful 7.36 mm bottle-necked cartridge originally designed for the Borchardt, the Mauser was the first semi-automatic pistol used extensively in battlefields, as in South African War of 1899-1902. The next notable design was the Luger Parabellum, featuring greatly improved Borchardt-type locking mechanism, by Georg Luger, which was adopted by the German military and served as their standard sidearm during World War I. During World War II Germany was the first nation to adopt a so called double action pistol, the Walther P38 which could be carried loaded and ready to fire at all times without the risk of an accidental discharge. Luger's 9 mm cartridge is the most widely used pistol cartridge today. In the United States, the first gun designer to develop self-loading pistols was John Browning, whose models were manufactured in Europe by the Belgian Fabrique Nationale and by Colt in the US. The .45 Colt M1911 was adopted by the US military and remained in service for over 70 years.

During World War II the only major powers to still resort to revolvers as sidearms were Britain, Russia and the United States. Though the British factory Webley and Scott had developed several adequate semi-automatic pistols, one of which was adopted by the British Police in 1911 and the Royal Navy and royal Marines before the First World War, their trusty revolvers were preferred by British military. In Russia the Nagant revolver remained the primary handgun because of a lack of pistols. In the United States, both Colt and Smith & Wesson produced revolvers chambered for the same pistol ammunition as used in the Colt 1911, because of the great demand for handguns.

After World War II most nations adopted 9mm Luger pistols for military use. The most popular being the FN Browning Hi-Power, which was the first high capacity pistol, the other popular model was the Walther P38 because of its many modern safety features. In 1971 Smith & Wesson was the first company to offer a safe double action high capacity pistol with its Model 59. CZ launched its CZ-75 in 1975. Beretta its Beretta 92 in 1976. GLOCK came up with the ultra modern GLOCK 17 in 1982 and SIG-Sauer introduced its model P226 in 1983. In the early 90s, Heckler und Koch combined what they thought were the most desirable attributes of semi-autos in their pistol, the HK USP.

After the second world war the semi-automatic pistols have replaced the revolvers used in the military and have also done so, although slightly more slowly, in police use. Today, revolvers are mainly found in the fields of civilian self-defence, hunting and target practice.

Famous semi-automatic handguns

The US, French and Italian military have adopted variants of the Beretta 92. The British military and US Navy SEALs the Sig P226. The Austrian, Finnish and Norwegian military the GLOCK 17.

On a worldwide basis the GLOCK 17 and GLOCK 22 have become the most widely used law enforcement pistols.

Popular examples:

See also


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