Editing M1 carbine (section)

==Variants==
{{More citations needed section|date=January 2021}}
The standard-issue versions of the carbine officially listed and supported were the M1, M1A1, M2 and M3.<ref>Department of the Army Technical Manual TM9-1276 and Department of the Air Force Technical Order TO39A-5AD-2, Cal. .30 Carbines, M1, M1A1, M2, and M3. February 1953.</ref>

[[File:M1A1 Carbine tri army.jpg|thumb|M1A1 carbine. Paratrooper model with folding buttstock and late issue adjustable sight and bayonet lug.]]

===Carbine, Cal .30, M1A1===<!-- [[M1A1]] links here -->
* Side-folding [[Stock (firearm)|stock]], 15-round [[Magazine (firearm)|box magazine]]
* [[Paratrooper]] model
* About 150,000 produced

The M1A1 was designed in May 1942 for paratrooper units, and came with a folding stock, but was otherwise identical to a standard M1.<ref>{{Cite book|last=Harrison|first=E.H.|title=U.S. Cal .30 Carbine|publisher=National Rifle Association|year=1992|page=6}}</ref> M1A1 carbines were made by Inland, a division of General Motors and originally came with the early "L" nonadjustable sight and barrel band without bayonet lug. Inland production of M1A1 carbines was interspersed with Inland production of M1 carbines with the standard stock. Stocks were often swapped out as carbines were refurbished at arsenals.

===Carbine, Cal .30, M1A2===
* Proposed variant with improved sight adjustable for windage and elevation
* Produced only as an "overstamped" model (an arsenal-refurbished M1 with new rear sight and other late M1 improvements)

===Carbine, Cal .30, M1A3===
* Underside-folding pantograph stock, 15-round magazine
* Type standardized to replace the M1A1 but may not have been issued
* Pantograph stock was more rigid than the M1A1's folding stock and folded flush under the fore end. A more common name for this type of stock is an "underfolder".

===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"/>

===Carbine, Cal .30, M2A1===
* M2 with an M1A1 folding stock. Like the M1A1, it was made for paratroopers.

===Carbine, Cal .30, M2A2===
* Arsenal-refurbished (over stamped M2) model

===Carbine, Cal .30, M3===
* M2 with mounting (T3 mount) for an early active (infrared) night vision sight
* About 3,000 produced
* Three versions of night sight (M1, M2, M3)

[[File:M3 Sniperscope.jpg|thumb|right|Original Korean War era USMC M3 night vision scope]]

The M3 carbine was an M2 carbine fitted with a mount designed to accept an infrared sight for use at night. It was initially used with the M1 sniperscope, and an active infrared sight, and saw action in 1945 with the Army during the invasion of Okinawa. Before the M3 carbine and M1 sniperscope were type-classified, they were known as the T3 and T120, respectively. The system continued to be developed, and by the time of the Korean War, the M3 carbine was used with the M3 sniperscope.

The M2 sniper scope extended the effective nighttime range of the M3 carbine to {{convert|100|yd|abbr=on}}. In the later stages of the Korean War, an improved version of the M3 carbine, with a revised mount, a forward pistol grip, and a new M3 sniperscope design was used in the latter stages of Korea and briefly in Vietnam. The M3 sniperscope had a large active infrared spotlight mounted on top of the scope body itself, allowing use in the prone position. The revised M3/M3 had an effective range of around {{convert|125|yd|abbr=on}}.<ref name="Article"/> Eventually, the M3 carbine and its M3 sniperscope would be superseded by passive-design night vision scopes with extended visible ranges; the improved scopes in turn required the use of rifle-caliber weapons with flatter trajectories and increased hit probability.