What’s the difference between M1 and M2 carbines?

Back in the 60s through the 80s, the M1 Carbine was the gateway drug to a life of gun collecting for many young Americans. It was as light and handy as a .22 (in fact, Ruger’s popular 10-22, and several other Ruger firearms, consciously copied the M1’s envelope and handling). It had next to no recoil, and they were common as dirt: millions of them were made (over five million and less than eight million), and even after distributing them generously to every friendly nation on the planet, there were still hundreds of thousands to flood the surplus market. 

The M1 was delivered in four versions: the M1 was the original, semi-auto gun with a wood, usually walnut or birch, stock. It had a characteristic slot in the stock for a sling, which was pinned to the stock by a metal tube containing gun oil for maintenance. The M1A1 was a paratrooper version with a folding steel stock with a leather cheekpiece. The stock was flimsy and its lockup (open or closed) was not positive, but it made a compact, handy gun even more so. (The oiler had a bracket it clipped to in the stock). The M2 added a selector to the left of the receiver ring that allowed the operator to select full- or semi-auto fire. The gun itself differed only in a few parts: the operating rod and hammer, and had three parts the semi gun did not: trip rod, auto disconnector, and, of course, the selector. M2s also had a superior magazine catch with three points of engagement instead of two, but this was retrofit on many, many M1s. The M3 was an M1 M2 (see comments for explanation of correction –Ed.) set up to take the Infrared Sniperscope, the first US night vision sight, instead of iron rear sight.

This video shows you the differences between the two guns.

The same guy has posted WWII-vintage videos on the M1 and M2 that are worth viewing if you’re a fan of these obsolete but ingenious weapons. The American Gunsmithing Institute’s armorer’s video on the M1/M2 carbines has a better explanation of the operating cycle than this one, but AGI would take a dim view of us posting that. They get something ridiculous like $40 for it.

As the video should make clear, there is very little mechanical difference between M1 and M2 carbines.

From time to time one hears about BATFE trying to make a constructive possession case on an M1 that has some M2 parts. This is not entirely on the level, as the M2 parts were in many of the M1s surplused and the ATF never objected then. Without all the M2 parts, no carbine will fire on automatic. With all the M2 parts, any M1/2/3 carbine will be a select fire gun. This means that you do have constructive possession exposure if you own a carbine and a full set of auto parts. It’s fairly ate-up, but that’s the law.

The carbine is interesting for many other reasons, including the short-stroke gas piston. It also was widely reproduced in civilian versions, many of which have upgrades or changes from the GI version. The later Universal carbines, for example, have an operating rod made from a thick steel stamping instead of the forged, machined or cast parts seen elsewhere.

The carbines were used with a straight 15-round magazine in WWII and Korea. GIs loved it for its handling and low recoil; against that, they disliked its limited effective range and weak terminal ballistics. General Jim Gavin was so disappointed in his carbine on Sicily that he threw it away and used an M1 rifle instead, choosing that for his Normandy jump also.

In US service, the carbine was replaced, sort of, by the much more unwieldy M14 rifle. (No one believes this unless they’ve put the two side-by side, but the M14 is longer as well as deeper than the M1 Garand). A carbine-sized weapon was still needed, which is why SF in Vietnam received the XM177 series “submachine gun” and why an evolution of that weapon was ultimately adopted as the M4 Carbine.

The M1/M2 carbines got a second lease on combat life during the Vietnam War. While to Americans the signature weapon of the war will always be the M16A1, the newer weapon was not supplied to ARVN regulars until after 1970. Prior to that point, both regular ARVN formations and irregulars like SF’s Civilian Indigenous Defence Groups were equipped with US WWII-vintage weaponry. The carbine quickly endeared itself to the small-statured Vietnamese troops.

We recall hearing a Vietnam-vintage SF friend discuss his choice of a carbine as his patrolling weapon. His M2 never let him down, and he liked having weapons commonality with his Cambodian indig (most of the irregulars recruited by SF in Vietnam were ethnic minorities).

6 thoughts on “What’s the difference between M1 and M2 carbines?

    1. Hognose Post author

      You know, that’s what I always heard, too, but I was going on the AGI video (which I’d just watched), figuring my memory was wrong. Going right to the source, FM 9-1276, dated 22 Jan 47. (This is the ordnance maintenance manual for the carbines). It says:

      CARBINE, CAL. .30, M3. This model is identical with the carbine, cal. .30, M2 except that the top of the receiver is designed to accommodate special sighting equipment (sniperscope) issued by the Corps of Engineers. Information on the Sniperscope may be found in TM 5-9341. There are no provisions made in this receiver for the conventional rear sight.

      There are several other references to the M3 as always having select fire capability. So yes, you’re right. When I get to it I’ll fix the post.

  1. Ceefour

    When I was in the business,an M3 was the “grease gun”…an auto firing machinegun which ate up .45 caliber cartridges

    1. GBS

      In the 1940s, an M1 was a rifle (two different ones, actually), and an M4 was a tank. For the last couple of decades, an M1 is a tank, and M4 is a rifle. The Army works in mysterious ways…

      1. Hognose Post author

        I think we’re not allowed to let numbers get beyond two digits, so the clerical personnel can continue to record them without having a stack memory overflow in their cranial wetware. In WWII an M3 was a carbine, a submachine gun, two utterly different tanks (light and medium), a halftrack, and a whole bunch of other things.

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