… we may as well share with you the overhaul manual on the M1/2/3 carbines. You know, these things:

This edition of FM 9-1276 was published in 1947 and it contains a lot of useful information, including the overhaul flow chart we’ve already shown you, and the very interesting inspection and rebuilt-weapon serviceability standards.

Most gun-culture types have a certain fetish for MilSpec and seem to think that military specs are always higher that civilians’ standards. Well, it depends on the civilian! But the military has looser requirements than you might think, and one characteristic of these requirements is that a weapon in the hands of troops is not required to meet standards of a weapon freshly rehabbed, or one being mothballed (figuratively) for that matter. For example, when the M16A1 was standard issue, one could be turned in for higher-echelon maintenance if the barrel was shot out. How shot out? The depot didn’t want to see it if it could still achieve seven (!) minutes of angle. Needless to say, crappy-shooting M16A1s were pure hell for a unit armorer to get rid of.

There are a few examples of this very, very low bar attending to the M1 (and M2 and M3) carbines. One of the most interesting is the high tolerance for pitting in the inspection standards. A barrel was only unfit if the pits were wider than a land or a groove, or longer than 3/8″. Pitting across most of a groove? Well, that was OK, then. Just so long as it’s not all the way across.

Anyway, here goes:

M1_Carbine_TM9-1276.pdf

If you pick up a typical M1 Carbine (or almost any US military surplus weapon, but let’s stick to carbines for reasons that will become obvious) at a gun show, you’ll find that it’s a mélange of parts from various makers and vintages. But occasionally, someone will have a gun that is, for example, all Inland parts. Obviously, the first one is a parts-gun junker, and the second one’s “as issued” back in W-W-Two, right?

Maybe not right. It could actually be the other way around: the first gun is just the way some GI carried it in WWII or Korea, and the second was carefully assembled from parts to catch a collector’s eye. Whaaat?

It has to do with how carbines were handled, maintained, and redistributed in the theaters or war and in the Zone of the Interior, as the US was still often called in the mid-20th Century. The flow chart on the left (which you’ll probably have to expand to read) spanned two pages of the M1/2/3 Carbine overhaul manual (FM 9-1276) and explains the steps in an overhaul.

Not every gun got overhauled, but every time Ordnance units got their hands on a gun, it was considered for it. To decide if they needed to do it, they had to inspect the gun, of course. Ordnance got guns when they were turned in by armorers as having “issues”, turned in as entire unit sets by traveling units, recovered from battlefields and field hospitals (to this day, if you enter a hospital with a weapon, some Gorgon of a nurse will take it away from you, muttering incantations to the Gods of Geneva), and various other means fair and foul. At lower echelons, any guns passing inspection or readily reparable would quickly go back out to line units as battlefield replacements.

Guns that needed depot attention would be greased up in Cosmoline and packed together in wooden crates, and shipped to that facility, where they’d enter the top left of the chart. They’d be taken out of the crates, which themselves would be sent to a specialty shop for repair and reconditioning, and dismantled. Individual parts would be inspected — some by eyeball, and some using gages — and repaired, if possible; serviceable parts whether from inspection or repair benches would be refinished and then go to a central parts bin.  (U/S parts were discarded).

In addition to the parts from the incoming carbines, the parts bins also held parts acquired under replacement-parts contracts, some makers of which never made complete carbines, only individual parts. None of the parts in the bins were labeled to a particular serial number of carbine. It was by way of this parts bin that most USGI carbines became mixmasters.

A very few parts were not removed from a carbine in this process. If the front and rear sights were serviceable, they stayed on board (Carbine rear sights were staked firmly in place, four times; front sights are simply a bear to remove and replace). And if the gas system worked and wasn’t visibly corroded, it wasn’t always disassembled. It’s possible to test the carbine gas system, on a field-stripped weapon, by the simple expedient of plugging the chamber with a finger or thumb, and blowing into the muzzle.

At the other end of the depot’s small arms bay, technicians (probably different ones from the ones stripping carbines at the intake end of the production line) would assemble carbines from the refinished, repaired or recertified parts in the parts bins. It had to pass a complete inspection and a live-fire function test, or it was repaired until it did. After test firing, the weapon was cleaned, inspected again (and sent again to the repair bench if need be, in which case it would be reinjected  at the test-fire station again), and greased and packed.

Then, cases of carbines (the same cases that carbines came in in, after they, too, were overhauled and repaired as necessary) were shipped to users worldwide, or stored in the depots until called for. The cases held 10 M1 or M2 carbines, and weighed 83 pounds, measured 39 3/8 x 10 3/4 x 10 3/4 inches, and displaced 4 cubic feet; 10 M1A1s in the same case weighed 91 pounds.

As you see, this means that the odds are astronomical against any carbine that has been through this process still possessing parts made by its original maker. Modern guns are made with precision, interchangeable parts with almost zero hand fitting, and this high-throughput WWII-vintage overhaul system took maximum advantage of that.

So if you have an Inland carbine with all Inland parts (or Winchester, etc.) then that gun either has never been through the overhaul process, or has been carefully reassembled by some collector, carefully hoarding parts over the years. And there’s no really obvious way to tell; even a couple of late-carbine parts might have been refitted to an early carbine at the unit level, and the Air Force, which kept toting carbines into the 1960s, was especially slapdash about rebuilds and repair parts (a tradition they kept up with M16s and GAUs).

Our advice: don’t get too wound up about Carbine originality — if you do, you’re probably going to get fished sooner or later. The officers, signalmen, medics, mortarmen, support troops and others who toted these in every theater of war, didn’t worry overmuch about these details. Neither should we.

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).