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.