Home > Semi-automatic pistol
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.1 Technology
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 gas pressure from the fired cartridge which drives the breechblock and slide backward, ejecting the spent cartridge's case and then pushing a new round from the magazine into the chamber when the recoil spring forces the slide back forward. 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 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.
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's unlocked when the barrel tips backward, after which the breechblock and slide continues backward without the barrel. Blowback pistols are simpler in construct and thus cheaper to manufacture, but the blowback mechanism can only be used with cartridges of relatively low power. With high power cartridges the breech would open too quickly, unless the breachblock was made very heavy, leading the pressure to rupture the case which would thus fail to eject.
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 cocked to fire. When the trigger would be pulled, the hammer would drop and 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 springA spring is a flexible elastic object used to store mechanical energy. Springs are commonly made out of steel or brass. Types of spring The most common types of spring are: the helical or coil spring (made by winding a wire around a cylinder) this is a ty. 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) will be heavier than when in single action mode. After the first shot the pistol will revert to single action mode because the rearward motion of the slide (which cycles the pistol) will cock the hammer; the trigger pull weight in single action mode will usually be 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 strikerThis article is about football players. See also striker (disambiguation). Strikers also known as centre forwards forwards and attackers are the players on a team in association football in the row nearest to the opposing team's goal, who are therefore pr systems also called "safe action" or "semi-double action", 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.
