In firearms, a safety or safety catch is a mechanism used to help prevent the accidental discharge of a firearm, helping to ensure safer handling.
Safeties can generally be divided into subtypes such as internal safeties (which typically do not receive input from the user) and external safeties (which typically allow the user to give input, for example, toggling a lever from "on" to "off" or something similar). Sometimes these are called "passive" and "active" safeties (or "automatic" and "manual"), respectively.
Firearms with the ability to allow the user to select various fire modes may have separate switches for safety and for mode selection (e.g. Thompson submachine gun) or may have the safety integrated with the mode selector as a fire selector with positions from safe to semi-automatic to full-automatic fire (e.g. M16).
Some firearms manufactured after the late 1990s include mandatory integral locking mechanisms that must be deactivated by a unique key before the gun can be fired. These integral locking mechanisms are intended as child-safety devices during unattended storage of the firearm—not as safety mechanisms while carrying. Other devices in this category are trigger locks, bore locks, and gun safes.
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The most common form of safety mechanism is a switch that, when set to the "safe" position, prevents a pull of the trigger from firing the firearm. Designs of such safeties are as varied as the designs of firearms themselves, but the two most common mechanisms are a block or latch that prevents the trigger and/or firing mechanism from moving, and a device that disconnects the trigger from the firing mechanism of the firearm. These are the oldest forms of "active" safety mechanism and are widely used; however many "double action" firearms such as revolvers do not have manual safeties as the longer, harder trigger pull to cock and fire double-action provides adequate trigger safety, while keeping the firearm in a more ready state.
A grip safety is a lever or other device situated on the grip of a firearm which must be actuated by the operator's hand, as a natural consequence of holding the firearm in a firing position, in order for the firearm to fire. It is usually similar to a manual safety in its function, but is momentary; the safety is deactivated only while the shooter maintains their hold on the grip, and is reactivated immediately once the shooter releases it. The M1911 design is a popular example of a handgun with a grip safety. The Uzi submachine gun is another example of a firearm with a grip safety.
A related grip-type safety is the decocking grip found on some H&K pistols like the P7 Series. The firearm is cocked and ready to fire only when the front of the grip is squeezed by the operator. When the grip is released, the firearm is decocked, and the single-action trigger will not cock the firearm, therefore it will not fire unless the grip is squeezed and the trigger pulled.
Another, unusual variant was found in the Ortgies semi-automatic pistols. To disengage the safety, a user would squeeze a lever until flush with the rear of the grip. The lever then would latch in the disengaged position until the user released it again by pressing a button under the slide, whereupon tension from the striker spring would push it back to the engaged position. Thus, engaging the safety also relieved some tension in the striker spring.[1]
Most traditional double-action semi-automatic (DA/SA) pistols are designed to be carried with the hammer down (uncocked) on a chambered round, with or without a manual safety engaged. The pistol is considered safe in this state as the "double-action" pull that both cocks and fires the firearm is both longer and heavier than the "single-action" pull that simply releases the cocked hammer. However, the act of cycling the action (slide or bolt) on such a firearm (as a natural consequence of discharging the firearm, or to chamber the first round) will leave the hammer cocked in single-action mode. To return the pistol to its safe state, it is necessary to uncock (decock) the hammer, usually by holding the hammer spur, carefully pulling the trigger, and then slowly lowering the hammer on the firing pin. This process is dangerous if done carelessly or in adverse conditions, and violates the third rule of gun safety; "keep your finger off the trigger until you are on target and ready to fire".
A decocker or manual decocking lever allows the hammer to be dropped on a live cartridge without risk of discharging it, usually by blocking the hammer or retracting or covering the firing pin before releasing the sear. This eliminates the need to control the fall of the hammer although, since all mechanisms can fail, it is necessary to keep the muzzle of the gun pointed in a safe direction while decocking.
A decock/safety is a combination manual safety switch and decocking lever. Two popular variants exist. In the "three-way" system, made popular by Heckler & Koch pistols, the handler may decock the firearm by pushing down on the safety lever from the "Fire" setting, or engage the safety (even on a cocked firearm) by pushing the lever upwards. A simpler "two-way" system was popularized by the Walther PP: engaging the safety also uncocks the firearm.
The Sig Sauer line of pistols, such as the SIG P226, frequently feature decocking levers. The earliest use of a single-action decocker was the Vis Wz 35 redesign in 1932 to enable horsemen to safely holster their firearm with one hand.[2] The earliest use of a cocking/decocking lever is the Sauer 38H from 1938. Ruger until 2007 manufactured "decock-only" variants of its P-series pistols, and the "two-way" decocking safety has been available on these pistols since their introduction.
Many jurisdictions such as the State of California require some form of "drop safety" on all new firearms, designed to reduce the chance of a firearm accidentally discharging when dropped or roughly handled. Such safeties generally provide an obstacle to operation of the firing mechanism that is only removed when the trigger is pulled, so that the firearm cannot otherwise discharge. Drop tests were introduced with the federal Gun Control Act of 1968 for imported guns.
A safety notch is one of the oldest forms of drop safety, used on older single-action revolvers manufactured before the invention of the hammer block, some lever action rifles, 1911-pattern guns, and hammer-fired semi-automatics that were designed before the invention of the firing pin block. The safety notch is a relief cut made in the tumbler that is connected mechanically to the hammer that allows the sear to catch and hold the hammer a short distance from the pin or cartridge primer, in a "half-cocked" position. The safety notch works first by allowing the handler to retract the hammer a short distance from the firing pin or primer, such that dropping the firearm on its hammer will not result in an energy transfer to the pin or spur, which could then discharge a chambered cartridge. A second purpose is to allow the sear to "catch" a hammer that is falling when the trigger has not been pulled, such as in cases where a drop jarred the sear loose or when the hammer was not fully cocked before being released. However, a safety notch used to "half-cock" a firearm is an active feature that must be engaged, and does not positively prevent accidental discharges in all cases. A certain amount of manual dexterity and familiarity with a firearm is also required to "half-cock" a firearm; unfamiliarity with how to engage the "half-cock" position can result in accidental discharges.
A firing pin block is a mechanical block used in semi-automatic firearms and some revolvers that, when at rest, obstructs forward travel of the firing pin, but is linked to the trigger mechanism and clears the obstruction to the pin just before the hammer or striker is released. This prevents the firing pin from striking a chambered cartridge unless the trigger is pulled, even if the hammer is released due to a faulty sear or the pin is dropped or struck by another object.
A hammer block is similar to a firing pin block. It is a latch, block or other obstruction built into the action and normally positioned to prevent the hammer contacting the cartridge primer or firing pin when at rest. Similar to the firing pin block, the obstruction to the hammer's travel is removed as a consequence of pulling the trigger. This allows the hammer to contact the primer or firing pin only when the trigger is pulled.
A transfer bar is also used in revolvers, but works the opposite way from a hammer block. The transfer bar has the spur that would otherwise be on the hammer, or encloses a firing pin similar to autoloading designs. The hammer itself cannot contact a loaded cartridge, but must instead strike the transfer bar, which then contacts the cartridge primer with the spur or pin. The transfer bar is normally positioned out of line with the hammer's travel, but is moved into place by the normal action of the trigger, providing similar "drop safety" to a firing pin block.
Popular on bolt, pump and lever-action firearms such as shotguns and rifles, a bolt interlock disengages or blocks the trigger if, for any reason, the bolt/breech is not in its fully closed, ready position. A variation is the trigger disconnect which prevents the gun from firing until the gun has not only been fully and completely cycled, but the trigger is released and squeezed again. This defines the behavior of semi-automatic firearms which require a separate trigger pull to fire each successive cartridge and ready the next, and this is the preferred mechanism of disengaging the trigger on repeating-action firearms. Older pump-action shotguns such as the Winchester Model 12 did not have such a feature, and as a result if the trigger was held the newly chambered round would be fired as soon as the breech had been closed.
Such disconnects or interlocks are generally simple to incorporate, and in fact are a by-product of many firearms' actions; pulling the trigger while the breech is unlocked or open does nothing as the mechanism is not fully reset until cycling is complete. As such these features are often not considered "true" safeties, although the interlock helps prevent misfires due to a bullet not being fully in the breech when its primer is struck by the pin (known as firing "out of battery"), and passing handguns or rifles to another person with the action open (known as "show clear") is recommended by elementary gun safety.
A magazine disconnect is an internal mechanism that engages a mechanical safety such as a block or trigger disconnect when the firearm's magazine is removed. This feature was first used with the Browning Hi-Power pistol. As with any firearm feature, there is debate regarding the necessity of a magazine disconnect. Historically, most magazine-capable firearm designs have had no magazine disconnect. There are exceptions, notably Ruger rimfire rifles and some of their newer handgun designs, and the U.S. State of California passed legislation in 2006 requiring magazine disconnects on all new handgun designs sold in the state starting January 1, 2007, which has resulted in their widespread availability in other jurisdictions as well.
The arguments in favor of a magazine disconnect are that if the gun cannot fire without a magazine, then an accidental discharge can be prevented if someone removes the magazine but forgets that a round has been chambered. Also, if losing possession of the firearm is imminent, the operator can render the firearm useless by removing the magazine.
The arguments against a magazine disconnect are that without a magazine the firearm is useless except as a club. Without the feature, if a magazine was lost or otherwise not available, then at least the gun could be chambered with a single round to be used as a single shot firearm. From a technical standpoint, a magazine disconnect adds extra parts to a firearm and thus increases complexity which creates additional risk of component failure while potentially increasing production costs. In some cases, the disconnect adversely affects trigger feel, and hence affects accuracy.
Some experienced firearms operators see little value in having a magazine disconnect due to their belief that proper firearm handling and care offer equal safety. Some also see magazine disconnects being introduced as a way to appease anti-gun politicians, while lessening firearm accuracy, reliability, and safety (for always keeping a defensive weapon ready to fire, even during a tactical reload during a firefight).
These safeties, similar to grip safeties, are de-activated as a natural consequence of the shooter firing the firearm, but are engaged in most other circumstances. The trigger is composed of two interdependent parts, and the shooter in firing the firearm manipulates both parts of the trigger. Conversely, unintentional pressure or a strike against the trigger is unlikely to do so, and such an action will not fire the firearm. Such a design, made popular by Glock pistols, incorporates a trigger with a spring-loaded lever in its lower half. This lever which protrudes from the trigger face must be fully depressed in order to disengage a lock that allows the main trigger body to move. Unintentional pressure against the top of the trigger without pressing the lever does not disengage the lock and the trigger will not move. Other designs include a spring-loaded pad that forms the upper portion of the trigger face and manipulates a similar lock. This design has more moving parts, but is advantageous in that accidental pressure on the lock release has reduced leverage thus requiring more force to pull the main trigger, where force against the lower portion does not release the lock and will not move the trigger.
Examples of the variety of typical semi-auto mechanisms are a stiff double-action trigger pull with the safety off (Beretta 92F/FS), a double-action with no external safety (SIG Sauer P-series, or Kel-Tec P-32), or a crisp single action trigger pull with a manual safety engaged (M1911, FN Five-seven and certain configurations of the HK USP). An alternative are striker-fired or "safe action" type firearms which have a consistent trigger pull requiring force greater than required by a single-action design, but lighter than needed for a double-action trigger. Many such firearms do not have an external safety or external hammer (Glock pistols and the Walther P99 and variants). In both cases, the action is very simple—a trigger pull always sends a discharge—and there are internal safeties to prevent non-trigger-pull discharge (e.g., dropping the gun).
Almost all modern semi-automatic handguns, except some exact replicas of antique models, have some form of safety mechanism including a "drop safety" that requires a trigger pull to discharge a cartridge. Single-action designs such as the Colt 1911 virtually always incorporate a manual safety, while traditional double-action pistols incorporate a decocker, manual safety, or both. However, the exact configuration depends on handgun type, year, make, and model. Double-action only (DAO) pistols, which usually use designs similar to traditional double-action but without the ability to remain cocked, do not usually have external safeties.
Single-action revolvers have no external safeties, and they usually have no internal safeties, such as a hammer block or transfer bar, to render them drop-safe. Most single action revolvers have a half-cock "safety" notch on the hammer, but many of these are not drop-proof. Real antiques are in this category; modern non-exact replicas may have internal hammer blocks. Carrying such firearms with a loaded chamber under the hammer, rather than with the hammer left down on an empty chamber, is not safe.
However, some single-action revolvers have relief cuts in between cylinder bores that allow the hammer to be rested directly upon the cylinder with no chance of interacting with loaded cartridges or primers. These are also known colloquially as "safety notches." They are usually found on black-powder revolvers, but there are also cartridge-firing revolvers with safety notches.
Most double-action revolvers have no external safety devices; a sufficiently firm trigger pull will always result in firing. The heavy trigger pull required to cock and then fire the firearm usually prevents accidental discharges due to dropping or mishandling the gun. Most modern double-action revolvers have an internal safety, either a hammer block or a transfer bar, that positively prevents firing without the trigger being pulled.
The only double-action revolvers with external safeties are unusual cases available only on special order or modified through aftermarket conversions.
Pistols made and imported by Glock incorporate a design with three levels of integrated safety, known as safe action; there are no external safety switches on these handguns. First, an integrated trigger latch prevents the trigger body from moving unless the trigger is positively squeezed. Second, the gun's striker-firing mechanism is locked in place by an extension bar linked to the trigger; the striker cannot move unless the trigger is depressed. Third, a firing pin block actuated by the same extension bar prevents the pin coming into contact with the primer unless the trigger is pulled to clear the block. Although not generally considered a safety feature, the resting state of the gun (excluding a dry/misfire) has the striker in a "half-cocked" state; pulling the trigger will fully cock the weapon before releasing the striker, and the mechanism is designed to have insufficient force to ignite the primer of an active cartridge from this state even if the sear lock and firing pin block both fail.
Rifles come with various safeties. Some use a cross-bolt safety button, others a wing safety at the rear, or even a "half-cock" notch (such as found on older lever action rifles.) The M1 Garand created a safety with a metal rocking lever at the front of the trigger guard that is now called the Garand-style safety, used in the Ruger Mini-14 rifle and Marlin Camp Carbine.
Some bolt action rifle safeties have three positions: "fire" which allows the gun to fire, "safe" which does not allow the gun to fire or the action to open, and an intermediate third position which cannot fire but allows the action to be opened to unload the rifle.
Common manual safeties for shotguns include button safeties located near or in front of the trigger guard and tang safeties located at the top rear (or "tang") of the receiver. Button safeties are either left- or right-handed, but tang safeties are ambidextrous.
Certain handguns manufactured with no external safety lever (on-off/armed-safe), such as double-action revolvers and Glock pistols, can have one added by aftermarket companies.