Editing M1 carbine (section)

===Carbine, Cal .30, M2===
[[File:US M2 Carbine.jpg|thumb|M2 carbine with the selector lever on the left side, opposite the bolt handle]]
[[File:M2CarbineGTAPage3.jpg|thumb|Exploded view of the M2 carbine]]
[[File:M2, Selector Switch.jpg|thumb|Close up of M2 carbine selector switch]]
* Mid to late 1944<ref>{{cite web | url=https://gunsmagazine.com/our-experts/the-m2-carbine/ | title=The M2 Carbine | date=31 January 2020 }}</ref><ref>{{cite web | url=https://warisboring.com/was-the-m2-carbine-americas-first-assault-rifle/ | title=Was the M2 Carbine America's First Assault Rifle? | date=18 December 2017 }}</ref>
* Selective fire (capable of semi-automatic or fully automatic fire)
* 15-round magazine or 30-round magazine
* About 600,000 produced

Initially, the M1 carbine was intended to have a selective-fire capability, but the decision was made to put the M1 into production without this feature. Fully automatic capability was incorporated into the design of the M2 (an improved, selective-fire version of the M1), introduced in 1944. The M2 featured the late M1 improvements to the rear sight, addition of a bayonet lug, and other minor changes.

Research into a conversion kit for selective fire began May 1944; the first kit was developed by Inland engineers, and known as the ''T4''. Inland was awarded a contract for 500 T4 carbines in September 1944. Although the conversion was seen as satisfactory, the heavier 30-round magazine put greater strain on the magazine catch, necessitating the development of a sturdier catch. The slide, sear, and stock design also had to be modified. On fully automatic fire, the T4 model could fire about 750 rounds per minute, and generated a manageable recoil.<ref name="Leroy_M1"/>

Although some carbines were marked at the factory as M2, the only significant difference between an M1 and M2 carbine is in the fire control group. The military issued field conversion kits (T17 and T18) to convert an M1 to an M2. Legally a carbine marked M2 is always a machine gun for [[National Firearms Act of 1934|national firearms registry]] purposes.<ref>{{cite web|url=https://www.atf.gov/firearms/firearms-guide-identification-firearms-section-1|title=Firearms Guide - Identification of Firearms |at=Section 1|access-date=19 August 2021|publisher=Bureau of Alcohol, Tobacco, Firearms and Explosive}}</ref>

These M2 parts including the heavier M2 stock were standardized for arsenal rebuild of M1 and M1A1 carbines.

A modified round bolt replaced the original flat top bolt to save machining steps in manufacture. Many sources erroneously refer to this round bolt as an "M2 bolt" but it was developed as a standard part for new manufacture M1 and later M2 carbines and as a replacement part, with priority given to use on M1A1 and M2 carbines.<ref name="Ruth"/> The slightly heavier round bolt did moderate the cyclic rate of the M2 on full automatic.<ref name="Small_Arms">{{cite book |last1=Smith |first1=W. H. B. |title=Small Arms of the World|publisher=Stackpole |date=May 1990|edition=12th|isbn=978-0-88029-601-4}} Illustrates an M2 carbine in an M1A1 stock on p.642 and a parts breakdown of the M2 on p.646 is shown with a flat top bolt.</ref>

Despite being in demand, very few M2 carbines saw use during World War II, and then mostly in the closing days against Japan.<ref name="Leroy_M1"/> The M2 carbine was logistically compatible with the millions of M1 carbines in U.S. service, and offered longer range, better accuracy and better penetration than (pistol caliber) submachine guns like the M1 Thompsons and [[M3 submachine gun|M3 Grease Guns]].<ref>{{cite magazine |title=America's Favorite Gun |first=Gold V. |last6=Sanders |magazine=Popular Science |date=August 1944 |pages=84–87, 221}}</ref> Therefore, after World War II, the M2 carbine largely replaced the submachine-guns in U.S. service, until it was itself replaced by the M16 rifle.<ref name="The M16 2011. page 6"/>

The M2 model was the most widely used carbine variant during the Korean War.<ref name="Leroy_M1"/> A detailed study of the effectiveness of the M2 in the war was assembled by [[S. L. A. Marshall]]. He found that many troops complained on the lack of effective range of the gun, which allowed the enemy to get close enough to throw [[hand grenade]]s. A more detailed analysis showed however that most troops who complained actually tended to run low on ammo, because they fired their M2 on fully automatic too soon. Troops who fired their guns on semi-automatic at distance generally complained less about the M2's effectiveness. Generally, the more seasoned troops used the latter approach. The carbine was usually given to second line troops (administrative, support, etc.), who had little combat experience and also did not have much training in [[small unit tactics|small-unit tactics]], but who usually had to engage the enemy at some critical moment, like a breakthrough or ambush. Marshall noted that almost all killing shots with carbines in Korea were at ranges of {{convert|50|yd|abbr=on}} or less. The M2 was a preferred weapon for [[night combat|night patrols]]. The M2 was also used in the early stages of the Vietnam War by special forces, [[ARVN]] advisers, and air crews.<ref name="Leroy_M1"/>

Contemporary authors have struggled to categorize the M2 carbine. While it did introduce select-fire capability and an intermediate cartridge, its stopping power and weight was far below that of the StG 44. As such, it is considered by some to be an early predecessor to the [[assault rifle]] or [[personal defense weapon]].<ref name="Leroy_M1"/>