Editing Carbine (section)

===Post World War II===
[[File:FAL IMG 1528.jpg|thumb|upright|[[FN FAL]] rifle – (left) full size, (right) carbine/paratrooper variant with a folding stock and shortened barrel]]
A shorter weapon was more convenient when riding in a truck, [[armored personnel carrier]], [[helicopter]], or aircraft, and also when engaged in close-range combat. Based on the combat experience of World War II, the criteria used for selecting infantry weapons began to change. Unlike previous wars, which were often fought mainly from fixed lines and trenches, World War II was a highly mobile war, often fought in cities, forests, or other areas where mobility and visibility were restricted. In addition, improvements in artillery made moving infantry in open areas even less practical than it had been.

The majority of enemy contacts were at ranges of less than {{convert|300|m|yd|abbr=off}}, and the enemy was exposed to fire for only short periods of time as they moved from cover to cover. Most rounds fired were not aimed at an enemy combatant but instead fired in the enemy's direction [[suppressive fire|to keep them from moving and from firing back]]. These situations did not require a heavy rifle, firing full-power rifle bullets with long-range accuracy. A less-powerful weapon would still produce casualties at the shorter ranges encountered in actual combat, and the reduced [[recoil]] would allow more shots to be fired in the short amount of time an enemy was visible. The lower-powered round would also weigh less, allowing a soldier to carry more ammunition. With no need of a long barrel to fire full-power ammunition, a shorter barrel could be used. A shorter barrel made the weapon weigh less, was easier to handle in tight spaces, and was easier to shoulder quickly to fire a shot at an unexpected target. [[Automatic firearm|Full-automatic]] fire was also considered a desirable feature, allowing the soldier to fire short bursts of three to five rounds, increasing the probability of a hit on a moving target.

The Germans had experimented with [[selective-fire]] carbines firing rifle cartridges during the early years of World War II. These were determined to be less than ideal, as the recoil of full-power rifle cartridges caused the weapon to be uncontrollable in full-automatic fire. They then developed an intermediate-power cartridge round, which was accomplished by reducing the power and the length of the standard [[7.92×57mm Mauser]] rifle cartridge to create the [[7.92×33mm]] {{lang|de|kurz}} (short) cartridge. A selective-fire weapon was developed to fire this shorter cartridge, eventually resulting in the [[Sturmgewehr 44]], later translated as "[[assault rifle]]" (also frequently called "machine carbines" by Allied intelligence, a quite accurate assessment, in fact). Very shortly after World War II, the USSR adopted a similar weapon, the ubiquitous [[AK-47]], the first model in the famed [[Kalashnikov rifle|Kalashnikov]] series, which became the standard Soviet infantry weapon and which has been produced and exported in extremely large numbers up through the present day.

Although the United States had developed the M2 carbine, a selective-fire version of the M1 carbine during WW2, the .30 carbine cartridge was closer to a pistol round in power, making it more of a [[submachine gun]] than an assault rifle. It was also adopted only in very small numbers and issued to few troops (the semi-automatic M1 carbine was produced in a 10-to-1 ratio to the M2), while the AK47 was produced by the millions and was standard-issue to all Soviet troops, as well as those of many other nations. The U.S. was slow to follow suit, insisting on retaining a full-power, [[7.62×51mm NATO]] rifle, the [[M14 rifle|M14]] (although this ''was'' selective fire).

In the 1950s, the British developed the [[.280 British]], an intermediate cartridge, and a select-fire [[bullpup]] assault rifle to fire it, the [[EM-2 rifle|EM-2]]. They pressed for the U.S. to adopt it so it could become a NATO-standard round, but the U.S. insisted on retaining a full-power, .30 caliber round. This forced NATO to adopt the [[7.62×51mm NATO]] round (which in reality is only slightly different ballistically from the .308 Winchester), to maintain commonality. The British eventually adopted the 7.62mm [[FN FAL]], and the U.S. adopted the 7.62mm [[M14 rifle]]. These rifles are both what is known as ''[[battle rifle]]s'' and were a few inches shorter than the standard-issue rifles they replaced ({{convert|22|in|adj=on}} barrel as opposed to {{convert|24|in}} for the M1 Garand), although they were still full-powered rifles, with selective fire capability. These can be compared to the even shorter, less-powerful assault rifle, which might be considered the "carbine branch of weapons development", although indeed, there are now carbine variants of many of the assault rifles which had themselves seemed quite small and light when adopted.

[[File:M855 drop during 25-meter zeroing trajectory M16A2 M4.jpg|thumb|left|Bullet drop of the M16A2 rifle (yellow) vs M4 carbine (red)]]
By the 1960s, after becoming involved in war in Vietnam, the U.S. did an abrupt about-face and decided to standardize on the intermediate [[5.56×45mm NATO|5.56×45mm]] round (based on the [[.223 Remington]] [[Varmint rifle|varmint cartridge]]) fired from the new, lightweight [[M16 rifle]], leaving NATO to hurry and catch up. Many of the NATO countries could not afford to re-equip so soon after the recent 7.62mm standardization, leaving them armed with full-power 7.62mm battle rifles for some decades afterwards, although by this point, the 5.56mm has been adopted by almost all NATO countries and many non-NATO nations as well. This 5.56mm NATO round was even lighter and smaller than the Soviet [[7.62×39mm]] AK-47 cartridge but possessed higher velocity. In U.S. service, the M16 assault rifle replaced the M14 as the standard infantry weapon, although the M14 continued to be used by [[designated marksmen]]. Although at {{convert|20|in}}, the barrel of the M16 was shorter than that of the M14, it was still designated a "rifle" rather than a "carbine", and it was still longer than the AK-47, which used a {{convert|16|in|adj=on}} barrel. (The [[SKS]] – an interim, semi-automatic, weapon adopted a few years before the AK-47 was put into service – was designated a carbine, even though its {{convert|20|in|adj=on}} barrel was significantly longer than the AK series' {{convert|16.3|in}}. This is because of the Kalashnikov's revolutionary nature, which altered the old paradigm. Compared to previous rifles, particularly the Soviets' initial attempts at semi-automatic rifles, such as the {{convert|24|in|adj=on}} [[SVT-40]], the SKS was significantly shorter. The Kalashnikov altered traditional notions and ushered in a change in what was considered a "rifle" in military circles.)

In 1974, shortly after the introduction of the 5.56mm NATO, the USSR began to issue a new Kalashnikov variant, the [[AK-74]], chambered in the small-bore [[5.45×39mm]] cartridge, which was a standard 7.62×39mm necked down to take a smaller, lighter, faster bullet. It soon became standard issue in Soviet nations, although many of the nations with export Kalashnikovs retained the larger 7.62×39mm round. In 1995, the [[China|People's Republic of China]] adopted a new [[5.8×42mm]] cartridge to match the modern trend in military ammunition, replacing the previous 7.62×39mm and 5.45×39mm round as standard.

Later, even lighter carbine variants of many of these short-barreled assault rifles came to be adopted as the standard infantry weapon. In much modern tactical thinking, only a certain number of soldiers need to retain longer-range weapons, serving as designated marksmen. The rest can carry lighter, shorter-ranged weapons for [[close quarters combat]] and suppressive fire. This is basically a more extreme extension of the idea that brought the original assault rifle. Another factor is that with the increasing weight of technology, sighting systems, [[Armour|ballistic armor]], etc., the only way to reduce the burden on the modern soldier was to equip them with a smaller, lighter weapon. Also, modern soldiers rely a great deal on vehicles and helicopters to transport them around the battle area, and a longer weapon can be a serious hindrance to entering and exiting these vehicles. Development of lighter assault rifles continued, matched by developments in even lighter carbines. In spite of the short barrels of the new assault rifles, carbine variants like the [[5.45×39mm]] [[AKS-74U]] and [[CAR-15|Colt Commando]] were being developed for use when mobility was essential and a submachine gun was not sufficiently powerful. The AKS-74U featured an extremely short {{convert|8.1|in|adj=on}} barrel which necessitated redesigning and shortening the [[Gas-operated reloading|gas-piston]] and integrating front sights onto the gas tube; the Colt Commando was a bit longer, at {{convert|11.5|in}}. Neither was adopted as standard issue, although the U.S. did later adopt the somewhat longer M4 carbine, with a {{convert|14.5|in|adj=on}} barrel.