Semi-automatic firearm

A semi-automatic firearm, also called a self-loading or autoloading firearm (<a href="/facts/Automatic_firearm/al4qSyv2">fully automatic</a> and <a href="/facts/Selective_fire/4uWp17JX">selective fire</a> firearms are also variations on <a href="/facts/Repeating_firearm/U7U612QQ">self-loading</a> firearms), is a <a href="/facts/Repeating_firearm/U7U612QQ">repeating firearm</a> whose <a href="/facts/Firearm_action/R2APeqab">action</a> mechanism automatically loads a following round of <a href="/facts/Cartridge_(firearms)/vjkWaDjM">cartridge</a> into the <a href="/facts/Chamber_(firearms)/X1Ekw5aK">chamber</a> and prepares it for subsequent firing, but requires the shooter to manually actuate the <a href="/facts/Trigger_(firearms)/e95STa6G">trigger</a> 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 <a href="/facts/Recoil/wGukfupU">recoil</a> or high-pressure gas expanding within the <a href="/facts/Gun_barrel/bPyBmQek">bore</a>) to unlock and move the <a href="/facts/Bolt_(firearms)/mEpdypQk">bolt</a>, 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, and 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.
<a href="/facts/Ferdinand_Ritter_von_Mannlicher/2H27S8sw">Ferdinand Ritter von Mannlicher</a> produced the first successful design for a semi-automatic rifle in 1885, and by the early 20th century, many manufacturers had introduced <a href="/facts/Semi-automatic_shotgun/zkDCXm9v">semi-automatic shotguns</a>, <a href="/facts/Semi-automatic_rifle/zrkhqcwG">rifles</a> and <a href="/facts/Semi-automatic_pistol/nlBHDhu2">pistols</a>.
In military use, the semi-automatic <a href="/facts/M1911/Wzb4l1cz">M1911</a> handgun was adopted by the United States Army in 1911, and subsequently by many other nations. Semi-automatic rifles did not see widespread military adoption until just prior to <a href="/facts/World_War_II/2efV5L1U">World War II</a>, the <a href="/facts/M1_Garand/YW1RH1dC">M1 Garand</a> being a notable example. Modern service rifles such as the <a href="/facts/M4_carbine/ncoafLmS">M4 carbine</a> are often selective-fire, capable of semi-automatic and automatic or <a href="/facts/Burst_mode_(weapons)/AbDboJ6q">burst-fire</a> operation. Civilian variants such as the <a href="/facts/AR-15_style_rifle/KQs3XBlg">AR-15</a> are generally semi-automatic only.

Semi-automatic firearm open-in-new

Semi-automatic firearm