A self-loading firearm is a

repeating firearm A repeating firearm or repeater is any firearm (either a handgun or long gun) that is designed for multiple, repeated firings before the gun has to be reloaded with new ammunition. Unlike single-shot firearms, which can only hold and fire a sin ...

that can use some of the excess energy released from

propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicle ...

combustion to cycle its

action Action may refer to: * Action (philosophy), something which is done by a person * Action principles the heart of fundamental physics * Action (narrative), a literary mode * Action fiction, a type of genre fiction * Action game, a genre of video gam ...

and facilitate loading of subsequent rounds of

ammunition Ammunition, also known as ammo, is the material fired, scattered, dropped, or detonated from any weapon or weapon system. The term includes both expendable weapons (e.g., bombs, missiles, grenades, land mines), and the component parts of oth ...

into the chamber, without needing the user to do any extra loading work with their hands. Depending on whether the action can automatically perform both the loading and ignition procedures, or only automatically load the ammo but require manual actuation of the

hammer A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nail (fastener), nails into wood, to sh ...

/ striker, self-loading firearms can be categorized into ''

automatic Automatic may refer to: Music Bands * Automatic (Australian band), Australian rock band * Automatic (American band), American rock band * The Automatic, a Welsh alternative rock band Albums * ''Automatic'' (Jack Bruce album), a 1983 el ...

'' and '' semi-automatic'' firearms.

Categories of self-loading weapons

Semi-automatic firearm

A semi-automatic firearm is a self-loading

whose

mechanism automatically loads a following round of cartridge into the chamber and prepares it for subsequent firing, but requires the shooter to manually actuate the

trigger Trigger may refer to: Arts, entertainment and media Fictional entities * Trigger (''Only Fools and Horses''), in the TV sitcom * Trigger Argee, in science fiction short stories by James H. Schmitz * Devil Trigger, a transformation ability of ...

in order to discharge each shot. Typically, this involves the weapon's action utilizing the excess energy released during the preceding shot (in the form of

recoil Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, for according to Newton's third law the force requ ...

or high-pressure gas expanding within the bore) to unlock and move the bolt, extracting and ejecting the spent cartridge case from the chamber, re-cocking the firing mechanism, and loading a new cartridge into the firing chamber, all without input from the user. To fire again, however, the user must actively release the trigger, allow it to "reset", before pulling the trigger again to fire off the next round. As a result, each trigger pull only discharges a single round from a semi-automatic weapon, as opposed to a fully automatic weapon, which will shoot continuously as long as the ammunition is replete and the trigger is kept depressed.

Automatic firearm

An automatic firearm or fully automatic firearm (to avoid confusion with

semi-automatic firearm A semi-automatic firearm, also called a self-loading or autoloading firearm ( fully automatic and selective fire firearms are also variations on self-loading firearms), is a repeating firearm whose action mechanism automatically loads a follo ...

s) is a self-loading

that continuously chambers and fires rounds when the

mechanism is actuated. The

of an automatic firearm is capable of harvesting the excess energy released from a previous discharge to feed a new

round Round or rounds may refer to: Mathematics and science * Having no sharp corners, as an ellipse, circle, or sphere * Rounding, reducing the number of significant figures in a number * Round number, ending with one or more zeroes * Round (crypt ...

into the chamber, and then igniting the

and discharging the

projectile A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found ...

(either

bullet A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. They are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax; and are made in various shapes and constru ...

, shot, or

slug Slug, or land slug, is a common name for any apparently shell-less Terrestrial mollusc, terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced ...

) by delivering a

or striker impact on the primer. If ''both'' the feeding and ignition procedures are automatically cycled, the weapon will be considered "fully automatic" and will fire continuously as long as the trigger is kept depressed and the ammunition feeding (either from a

magazine A magazine is a periodical literature, periodical publication, print or digital, produced on a regular schedule, that contains any of a variety of subject-oriented textual and visual content (media), content forms. Magazines are generally fin ...

or a belt) remains available. In contrast, a firearm is considered " semi-automatic" if it only automatically cycles to chamber new rounds (i.e.

self-loading A semi-automatic firearm, also called a self-loading or autoloading firearm (automatic firearm, fully automatic and selective fire firearms are also variations on repeating firearm#Autoloading, self-loading firearms), is a repeating firearm who ...

) but does not automatically fire off the shot unless the user manually resets (usually by releasing) and re-actuates the trigger, so only one round gets discharged with each individual trigger-pull.

References

External links

* NPR Audio Report
The Appeal of Semi-Automatic Weapons
{{DEFAULTSORT:Semi-Automatic Firearm Firearm actions Firearms