Gas-operated reloading in the context of "Heckler "

The Heckler & Koch G36 (German: Gewehr 36) is an assault rifle designed in the early 1990s by German weapons manufacturer Heckler & Koch. It is chambered in 5.56×45mm NATO, and replaced the heavier G3 battle rifle chambered in 7.62×51mm. The G36 was accepted into service with the Bundeswehr in 1997. Since then, it has been a popular export, and has seen active service in military and police units in several countries, including Germany, Spain, and the United Kingdom. The G36 is gas-operated and feeds from a 30-round detachable box magazine or 100-round C-Mag drum magazine.

In 2012, the G36 was found to suffer from significant accuracy issues due to thermal expansion of the barrel, prompting a search for a replacement. In 2017, the Bundeswehr launched the System Sturmgewehr Bundeswehr, a program designed to field a replacement for the G36. The weapons put forth were the Heckler & Koch HK416, Heckler & Koch HK433, and the Haenel MK 556. The G95A1 and G95KA1, both variants of the HK416, were selected in 2022.

A repeating rifle is a single-barreled rifle capable of repeated discharges between each ammunition reload. This is typically achieved by having multiple cartridges stored in a magazine (within or attached to the rifle) and then fed individually into the chamber by a reciprocating bolt, via either a manual or automatic action mechanism, while the act of chambering the round typically also recocks the hammer/striker for the following shot. In common usage, the term "repeating rifle" most often refers specifically to manual repeating rifles (e.g. lever-action, pump-action, bolt-action, etc.), as opposed to self-loading rifles, which use the recoil, gas, or blowback of the previous shot to cycle the action and load the next round, even though all self-loading firearms are technically a subcategory of repeating firearms.

Repeating rifles were a significant advance over the preceding single-shot, breechloading rifles when used for military combat, as they allowed a much greater rate of fire. The repeating Henry rifle was used by the infantry and Spencer rifle was used by the cavalry during the American Civil War and the subsequent American Indian Wars, and the first repeating air rifle to see military service was the Windbüchse rifle.

A semi-automatic pistol (also called a self-loading pistol, autopistol, or autoloading pistol) is a repeating handgun that automatically ejects and loads cartridges in its chamber after every shot fired, but only one round of ammunition is fired each time the trigger is pulled. The pistol's fire control group disconnects the trigger mechanism from the firing pin/striker until the trigger has been released and reset manually, unlike the self-cycled firing mechanism in fully automatic pistols.

A semi-automatic pistol recycles part of the energy released by the propellant combustion to move its bolt, which is usually housed inside the slide. After a round of ammunition is fired, the spent cartridge casing is extracted and ejected as the slide/bolt moves rearwards under recoil, the hammer/striker is cocked by the slide/bolt movement, and a new round from the magazine is pushed into the chamber when the slide/bolt returns forward under spring tension. This sets up the following shot (i.e. "in battery"), which is fired as soon as the trigger is pulled again. Most pistols use a short recoil operation to perform this, but some pistols use simple blowback or gas operation mechanisms.

The ArmaLite AR-15 is a gas-operated assault rifle manufactured in the United States between 1959 and 1964. Designed by American gun manufacturer ArmaLite in 1956, it was based on its AR-10 rifle. The ArmaLite AR-15 was designed to be a lightweight rifle and to fire a new high-velocity, lightweight, small-caliber cartridge to allow infantrymen to carry more ammunition.

In 1959, ArmaLite sold its rights to the AR-15 to Colt due to financial difficulties and limitations in terms of manpower and production capacity. After modifications (most notably, the charging handle was re-located from under the carrying handle like AR-10 to the rear of the receiver), Colt rebranded it the Colt 601, however, it still carried the Armalite markings due to contractual obligations to Armalite/Fairchild Aircraft Co. Colt marketed the redesigned rifle to various military services around the world and was eventually adopted by the U.S. military in January 1962 and subsequently designated as M16 rifle in December 1963, which went into production and service in 1964.

The AKM (Russian: Автома́т Кала́шникова модернизи́рованный Avtomat Kalashnikova modernizirovannyy, "Kalashnikov automatic modernized") is a 7.62×39 mm Soviet assault rifle introduced in 1959 as a lighter, more modern successor to the AK-47.

Designed by Mikhail Kalashnikov, it became the most widely produced variant of the Kalashnikov series, serving as the standard service rifle of the Soviet Army and Warsaw Pact states. Featuring a gas‑operated rotating bolt, slanted muzzle compensator, and simplified manufacturing for cost‑effective mass production, the AKM enhanced automatic accuracy and reliability while reducing weight by approximately 1 kg.