Gun safety

Barrel for dry firing, in order to ultimately check the unloaded state of a firearm

Many firearm accidents result from the handler mistakenly believing a firearm is emptied, safetied, or otherwise disarmed when in fact it is ready to be discharged. Such misunderstandings can arise from a number of sources.

• Faulty handling of the firearm. A handler may execute the steps of procedures such as loading, firing and emptying in the wrong order or omit steps of the procedures.
• Misunderstandings about a firearm's status. For instance, a handler may think the safety is on when it is not. A round of ammunition may be left in the chamber or in the magazine while the handler thinks it is emptied. The firearm may have been handled by another individual without the handler's knowledge. A handler may receive a firearm and assume it is in a certain state without checking whether that assumption is true. For example, as handlers interact and pass the firearm between them, each avoids over-relying on the "show clear" of the other. Person 1 may misjudge the status; person 2 cannot assume that "it's OK because person 1 already checked it".
• Mechanical failures. Wear, faulty assembly, damage or faulty design of the firearm can cause it not to function as intended. For instance, a safety may have been worn down to a point where it is no longer functioning. Broken or worn parts in the trigger, sear or hammer/striker may have given the firearm a "hair trigger" (a very sensitive trigger). A dented or bent body of the firearm may cause jams or premature discharge of ammunition. Sensitivity to impact may cause a firearm to discharge if dropped or struck against another object. A broken extractor may result in a round remaining in the chamber even when the otherwise proper steps have been taken to unload the weapon.

If a handler always treats firearms as capable of being discharged at any time, the handler is more likely to take precautions to prevent an unintentional discharge and to avoid damage or injury if one does occur.[11]

An example of not following the proper trigger discipline (the soldier's finger is on the trigger); the pistol could also be pointed in the direction of non-targets

Also known as muzzle discipline, this rule is intended to minimize the potential damage caused by an unintended discharge. While the first rule teaches that a firearm must be assumed to be ready to fire, this second rule goes beyond that and says, "Since the firearm might fire, assume that it will and make sure no harm occurs when it does." The rule is sometimes alternately stated as "Never point a firearm at anything unless you intend to destroy it."

Two natural safe directions to point the muzzle are up (at the sky) and down (at the ground). Both have their advantages and disadvantages. Firing at the ground may result in a ricochet or cause hazardous fragments to be flung at people or objects. Aiming upward eliminates this risk but replaces it with the risk that the bullet may cause damage when it comes down to the ground again. A bullet fired straight up only returns at the terminal velocity of the bullet.[12] However, a bullet fired at an angle not perfectly vertical will retain its spin and ballistic stability on the way down and can attain much more lethal speeds.[13] Several accidents have reportedly been caused by discharging firearms into the air; although the evidence in a few such cases has been disputed,[12] a study by the Centers for Disease Control and Prevention found 43 likely cases of injury from falling bullets during 2004 New Year celebrations in Puerto Rico.[14] It is also possible that the muzzle will inadvertently be pointed at a non-target such as someone's head or an aircraft.[15]

In cases where the firearm is being handled indoors, up and down may not be safe directions. For example, a bullet fired upward or downward may travel through the ceiling, floor and plenum between adjacent floors of a multi-story building. In indoor areas where firearms will be handled often, a suitably safe direction should be designated. Firing ranges often designate a direction in which it is safe to point a firearm; almost universally this is downrange into a backstop which is designed to contain bullets and eliminate potential ricochets. In armories or other areas where weapons must be handled, a container filled with sand known as a clearing barrel or clearing can is often used for this purpose; bullets unintentionally discharged into the barrel will be safely stopped and contained by the sand.

Finger off the trigger and outside the trigger guard

Also known as trigger discipline, this rule is intended to prevent an undesired discharge. Normally a firearm is discharged by depressing its trigger. A handler's finger may involuntarily move for any of several reasons: the handler is startled, a lack of full attention on body movements, physiological reasons beyond conscious control such as a spasm, stumbling or falling, or the finger being pushed by something (as when trying to holster a firearm with one's finger on the trigger). Handlers are therefore taught to minimize the harmful effects of such a motion by keeping their finger off and far away from the trigger until the muzzle is pointing at the target and the handler wishes to discharge the firearm.

The trigger guard and the receiver area above the trigger of a firearm presents a natural point for a handler to keep their finger out straight alongside the weapon, so as not to violate this rule. Another recommendation is to keep the trigger finger above the trigger guard, so that there is less chance of the finger involuntarily slipping into the guard when startled.[16] A properly indexed trigger finger also helps remind the person holding the firearm of the direction of the muzzle.

This rule is intended to eliminate or minimize collateral damage to non-targets when a firearm is intentionally discharged. Unintended damage may occur if a non-target is misidentified as a target, if the target is missed, or if the bullet hits something or someone other than the intended target.

Handlers are taught that they must positively identify and verify their target. Additionally, they learn that even when firing at a valid target, unintended targets may still be hit, for three reasons:

• The bullet may miss the intended target and hit a non-target around or beyond the target.
• A non-target may pass in front of the target and be hit with a bullet aimed at the target.
• The bullet may pass through the intended target and hit a non-target beyond it, so-called "overpenetration".

Therefore, this rule requires a handler to "always be sure of your target; not just the target itself, but above, below, to the left, to the right, in front of, and behind the target".

This may create situations that present dilemmas for a handler. Such situations are for instance a police officer in a riot with bystanders, a civilian facing a possible intruder at night, or a soldier in a confrontation where civilians are near the enemy. Indecision or misjudgment of the handler's abilities in such a situation may cause undesired outcomes, such as injury to the handler due to hesitation, or the handler violating rules of engagement and causing unintended damage.

Hunters are commonly prohibited from shooting across roads and trails, or after dusk and before dawn, due to the risk of inadvertently hitting an unintended target. All discharge of firearms is prohibited in some cities, in part due to the possibility of hitting unseen targets.

Training is used to minimize the risk of such outcomes. Target practice increases the precision with which the handler can discharge the firearm and thus increase the chances that the intended target is hit. Education about terminal ballistics gives the handler knowledge about the characteristics of a bullet after a target is hit. This knowledge coupled with insight into the handler's own capabilities makes it easier for the handler to make appropriate decisions about whether to discharge or not, even if given little time and/or put under severe stress.

Ammunition can be chosen to reduce the risk of overpenetration; see Terminal ballistics, Stopping power, and Hollow point bullet.

Ranges and organized shoots may impose additional safety rules on participants. For example, at its marksmanship clinics, Project Appleseed requires that a range safety officer (RSO) uses a weed trimmer line to check each rifle's bore for obstructions prior to its first use for the day. Six steps are then always followed when a round of shooting is complete and the line is ready to go "cold" to allow posting or checking targets also , or when a rifle is ready to be removed from the line: 1) magazine out; 2) bolt back; 3) safety on; 4) chamber flag in; 5) ground the rifle; 6) step back; no one touching the rifle.

Open bolt indicators, or chamber flags, such as the yellow safety flag distributed by the Civilian Marksmanship Program or the green chamber flag distributed by Project Appleseed, may be required to be inserted in the chamber to show the chamber is empty.

Ranges may limit the type of ammunition used, such as prohibiting the use of incendiary, tracer, or armor-piercing rounds, or more powerful rounds than a range is equipped to handle.[17][18] They may require the use of ear and eye protection.[18] Alcohol is commonly forbidden. Some ranges impose a waiting period for shooters who wish to rent a firearm, or require them to bring a friend, in order to reduce the incidence of suicides.[19][20] Ranges are advised to designate a range safety officer to enforce these rules.[18]

Ranges must be designed with safety in mind, including the use of proper backstops for the intended type of shooting.[18]

Malfunctions associated with the firing pin of a firearm, with the primer, or powder within a cartridge, include failures to discharge (misfires, duds), delayed discharge (hang fires), and incomplete or insufficient discharge (squibs). A misfire is when the cartridge does not fire after it is struck by the firing pin. A hangfire is when the firing pin strikes the cartridge, but there is a delay of some seconds before the cartridge finally fires. A squib is when an underpowered round is fired, perhaps with an insufficient amount of powder in the case, and the bullet lodges in the bore. If the firearm is fired again, the barrel can peel back, severely damaging the weapon and injuring the shooter.

In each case, the shooter should wait for a period of time, commonly recommended between 25 seconds, up to two minutes, with the firearm pointed in a safe direction, then carefully remove the magazine, extract any mis-fed or misfired cartridge(s), and, with the breech opened carefully, check to ensure there is not a bullet or other obstruction lodged in the bore of the barrel. If there is an obstruction, and a subsequent round is fired, the firearm can fail explosively resulting in serious injury. Misfired rounds should be disposed of properly, usually in a special container for live ammo that failed to fire after ejecting round; such rounds should not be simply disposed of in the trash.

Mechanical malfunctions of firearms include slamfires, out-of-battery discharges, jams, accidental release of the firing pin, and failure of the breech or barrel to contain the propellant.

A slam fire is when a cartridge fires immediately upon being chambered, before a trigger squeeze, and is most often caused by a floating firing pin that becomes obstructed by debris, or by an improperly raised primer that is installed on a cartridge case. A slamfire can also be caused by a softer primer being used than normally recommended, commonly in military firearms, which usually use cartridges with relatively hard primers.

Out-of-battery discharges occur when a cartridge is not correctly secured by the bolt but can be fired by the firearm's firing pin. Out-of-battery discharges can be initiated by either the operator deliberately releasing the firing pin or as a slamfire. Out-of-battery discharges often cause extreme damage to the firearm, particularly on the bolt, firing pin, magazine, and receiver as well as injure the operator and nearby observers. Eye damage and blinding are common injuries caused by out-of-battery firings. Eye protection, such as shooting glasses, are highly recommended for avoiding eye injuries. Out-of-battery discharges can be avoided by careful understanding of the firearm's operating mechanism.

Types of jams include failures to feed, extract, or eject a cartridge; failure to fully cycle after firing; and failure of a recoil- or gas-operated firearm to lock back when empty (largely a procedural hazard, as a slide lock is a visual cue that the firearm's ammunition supply is empty). When a jam occurs, the handler should exercise extreme caution as a cartridge whose primer has been struck and which has been deformed in a jam can discharge unexpectedly (in a hang-fire). One method of quickly clearing a jammed semi-automatic weapon is tap rack bang.

Firearms may also fire unintentionally for several reasons, including dropping the weapon or when a firearm receives any hard mechanical shocks. Similarly, unintentional firing may occur due to faulty triggers, or excessive heat buildup in the chamber which leads to the propellant cooking off. To prevent accidental firing when firearms are dropped or jarred, experts often suggest using modern firearm designs that have safety features such as a transfer bar or a firing pin block which prevent the firing pin from striking the primer unless the trigger is squeezed. For older firearms without these features, experts suggest that they should be carried without a round in the chamber, or with the firing pin resting on an empty chamber in the case of revolvers.[21]

Firearms may undergo catastrophic failure (a "kaBoom" or "kB") due to various causes, some caused by mishandling and others by poor design, weakened parts or the use of ammunition for which the firearm was not designed, but which will chamber and fire nonetheless.[22] Barrels may become blocked by foreign material, such as dirt, snow, or even water. For that reason, the muzzle should never be allowed to rest on the ground or allowed to accumulate precipitation. Another form of mishandling is the use of a cartridge that generates more pressure than the firearm was designed for. This can occur through faulty handloading, or the use of overpressure ammunition (+P or +P+) or magnum loads in firearms not rated for them.

A gun safe or gun cabinet is commonly used to physically prevent access to a firearm. Local laws may require particular standards for the lock, for the strength and burglar resistance of the cabinet, and may even require weapons and ammunition to be stored separately.

Access to a functioning firearm can be prevented by keeping the firearm disassembled and the parts stored at separate locations. Sometimes, this rule is codified in law. For example, Swedish law requires owners of firearms either to store the entire firearm in a safe or lockable gun rack, or to lock the "vital piece" (bolt, etc.) away in a safe place.

Trigger lock fitted to the trigger of a revolver

There are several types of locks that serve to make it difficult to discharge a firearm. Locks are considered less effective than keeping firearms stored in a lockable safe since locks are more easily defeated than approved safes. An unauthorized handler can bypass the locked firearm at their leisure.[23] Some manufacturers, such as Taurus, build locks into the firearm itself.

California effected regulations in 2000 that forced locks to be approved by a firearm safety device laboratory via California Penal Code Section 12088.[24] All locks under this code must receive extensive tests including saw, pick, pull, and many other tests in order to be approved for the state of California. If a lock passes the requirements then it is said to be California Department of Justice (CADOJ) approved.[25]

Trigger locks prevent trigger manipulation, however they do not guarantee that the firearm absolutely cannot be discharged (see above). Some trigger locks are integrated into the design of the weapon, requiring no external parts besides the key. Generally, two pieces come together from either side behind the trigger and are locked in place, which can be unlocked with a key or combination. This physically prevents the trigger from being depressed to discharge the weapon. Other more commercially common types of trigger locks do not go behind the trigger, but encompass the full area within the trigger guard to making the trigger inaccessible to users. Identilock is an attachment that completely covers and prevents access to the trigger, which makes it different from other trigger locks.

There is controversy surrounding manufacturing standards, usage, and legislation of trigger locks. While supporters of trigger locks argue that they will save children by preventing accidents, critics point to demonstrations that some models can be removed by children with very little force and common household tools. Many firearms can go off if it is dropped. It is important to make sure to look for firearms that fully disengage the hammer when the safety is put on. A former senior product manager at Master Lock, a trigger lock manufacturer, was quoted as saying "If you put a trigger lock on any loaded gun, you are making the gun more dangerous."[26] Critics also point out that a trigger lock will increase the time it takes an owner to respond to a self-defense emergency. In 2008, the U.S. Supreme Court overturned a Washington, D.C. law that required handguns to be locked or otherwise kept inoperative within the home, saying that this "makes it impossible for citizens to use them for the core lawful purpose of self-defense."[27]

Although there are no universal standards for the design or testing of trigger locks, some jurisdictions, such as the state of California, maintain a list of approved trigger lock devices.[28] In Canada, a trigger lock is one of the methods prescribed by law to secure a firearm during transport or storage.[29]

Chamber locks aim to block ammunition from being chambered, since most firearms typically cannot be discharged unless the ammunition is in the correct position. They are used to prevent live ammunition from being loaded into a firearm by blocking the chamber with a dummy cartridge or a chamber plug, which is sometimes wedged into place with the use of a tool, in essence jamming the firearm. Another type is one in which a steel rod locked into the safety cartridge with a key. As long as the rod and safety cartridge are engaged, the dummy round cannot eject nor can live ammunition be loaded into the firearm. Chamber locks work with most firearm types including revolvers, pistols, rifles and shotguns. They are available in any caliber and length, and may include such features as unique keying, rapid removal, and rigorous testing and certification by major state departments such as the California Department of Justice.

Some shooting ranges require the handler to insert a temporary chamber plug which often has a brightly colored external tag, to signal the chamber being devoid of ammunition and blocked, whenever the firearm is being unused. These are called empty chamber indicators, or chamber flags.

Cable locks are a popular type of lock that usually threads into the receiver through the ejection port of repeating firearms. These locks physically obstruct the movements of the bolt, thereby preventing the cycling of the action, and deny the return to "battery" and the closure of the breech. In many designs of pistol and rifle, they also thread through the magazine well of the firearm to prevent the proper insertion of a magazine.

Personalized firearms, or smart guns, are intended to prevent unauthorized use with built-in locks that are released by RFID chips or other proximity devices, fingerprint recognition, magnetic rings, or a microchip implant.[30]

Some experts recommend storing ammunition in secure locations away from firearms.[31] Ammunition should be kept in cool, dry conditions free from contaminating vapors to prevent deterioration of the propellant and cartridge. Handloaders must take special precautions for storing primers and loose gunpowder.

When a firearm is discharged it emits a very loud noise, typically close to the handler's ears. This can cause temporary or permanent hearing damage such as tinnitus. Hearing protection such as earplugs, or earmuffs, or both, can reduce the risk of hearing damage.[23] Some earmuffs or headphones made for shooting and similar loud situations use active noise control. Firearms may also have silencers which reduce the sound intensity from the barrel.

A firearm emits hot gases, powder, and other debris when discharged. Some firearms, such as semi-automatic and fully automatic firearms, typically eject spent cartridge casings at high speed. Casings are also dangerously hot when ejected. Revolvers store spent casings in the chamber, but may emit a stream of hot gases and possible fine particulate debris laterally from the interface between the revolving chamber and the barrel. Any of these may hurt the handler or bystanders through burning or impact damage. Because eyes are particularly vulnerable to this type of damage, eye protection should be worn to reduce the risk of injury. Prescription lenses and various tints to suit different light conditions are available.[23] Some eye protection products are rated to withstand impact from birdshot loads, which offers protection against irresponsible firearms use by other game bird shooters.[32]

In recent years the toxic effects of ammunition and firearm cleaning agents have been highlighted.

• Lead ammunition left in nature may become mobilized by acid rain.
• Older ammunition may have mercury-based primers.
• Lead accumulates in shooting range backstops.

Indoor ranges require good ventilation to remove pollutants such as powder, smoke, and lead dust from the air around the shooters. Indoor and outdoor ranges typically require extensive decontamination when they are decommissioned to remove all traces of lead, copper, and powder residues from the area.

Lead, copper and other metals will also be released when a firearm is cleaned. Highly aggressive solvents and other agents used to remove lead and powder fouling may also present a hazard to health. Installing good ventilation, washing hands after handling firearms, and cleaning the space where the firearm was handled lessens the risk of unnecessary exposure.

Firearms should never be handled by persons who are under the influence of alcohol or any drugs which may affect their judgment. Gun safety teachers advocate zero tolerance of their use.[33] In the United States, this recommendation is codified in many states' penal codes as a crime of "carrying under the influence", with penalties similar to DWI/DUI.[34] Other sources of temporary impairment include exhaustion, dehydration, and emotional stress. These can affect reaction time, cognitive processing, sensory perception, and judgment.

Many jurisdictions prohibit the possession of firearms by people deemed generally incapable of using them safely, such as the mentally ill or convicted felons.

Children who are generally considered too young to be allowed to handle firearms at all can be taught a different set of rules:

• Stop.
• Don't touch.
• Leave the area.
• Tell an adult.

The purpose of these rules is to prevent children from inadvertently handling firearms. These rules are part of the Eddie Eagle program developed by the National Rifle Association for preschoolers through 6th graders.[35]

Whether programs like Eddie Eagle are effective has not been conclusively determined. Some studies published in peer-reviewed journals have shown that it is very difficult for young children to control their curiosity even when they have been taught not to touch firearms.[36] Gun access is also a major risk factor for youth suicide.[37] The American Academy of Pediatrics (AAP) advises that keeping a gun in the home, especially a handgun increases the risk of injury and death for children and youth in the home.[38] If families do keep a gun in the home, the AAP advises keeping it unloaded and locked up, with the ammunition locked in a separate location, and the keys to the locked boxes hidden.[38]

Older youth (age may vary per program, such as 12–18 year olds) may take part in a program for safe rifle handling, such as the ones promoted by these organizations:

• 4H Shooting Sports Programs
• Boy Scouts of America
• Civilian Marksmanship Program
• National Rifle Association
• Project Appleseed

• Technical fault of a pistol at a firing range. Despite proper trigger discipline, the firearm discharged. Keeping it pointed in the correct direction prevented the event turning into an accident.
• Finger on trigger while tripping resulted in two accidental discharges
• Accidental discharge while showing off a handgun