November 13, 2023
There has always been interest in restoring M1 Carbines to wartime production configuration. The demand for original specimens and the lack of availability have made prices prohibitive for many collectors and shooters. This series will focus on the restoration process of an M1 Carbine equipped with post-World War II modifications including incorrect parts. Let us begin.
Determining a Part’s Originality
Originally, there were 11 prime contractors, i.e., “primes,” for manufacturing the M1 Carbine. These were reduced to 10 in April 1943 when Irwin Pederson Arms Manufacturing (IP) defaulted on its contract. Additionally, there were more than 1,500 parts subcontractors, i.e., “subs,” supporting the primes. Each prime and sub had letter codes assigned, which were stamped on parts to identify the maker.
It can be difficult to determine the parts that belong on a particular Carbine because a lot of these rifles did not have part-manufacturer codes matching the prime and subs. Therefore, be careful and do a lot of research before replacing parts on an M1 Carbine. Sometimes, the rifle will have a lot of correct-era parts that do not have codes believed to be correct. I recommend sourcing a copy of Jesse Harrison’s “Collecting the M1 Carbine” for detailed information on part markings.
Wear is a factor in determining the originality of a part to an M1 Carbine. Examine the wear pattern across multiple parts. The edge and surface wear of external parts should be similar. If you have a receiver and a barrel with a similar finish, and other parts look new or present less wear, the latter is probably not original to the gun. Authentic M1 Carbines are rare, difficult to find, and hard to identify. There are a lot of counterfeit, so-called “originals,” making a way through the market.
This series is not about returning an M1 Carbine to “as-produced” condition for both parts and manufacturers. Here, our final goal is to restore a Carbine with the correct “type” of parts for the era it was produced in.
No single prime made all the parts for an M1 Carbine. To complicate matters, there was a considerable sharing of parts between primes and subs to keep production going. This was prevalent through mid-1943 when the eight smaller primes were setting up for production. It continued through the end of production, but at a lesser extent until the termination of the eight smaller prime contracts. All contracts were terminated, except for Inland Division of General Motors (I) and Winchester Repeating Arms Co. (W) in late Spring 1944. At this time, parts were shared and sent throughout the industry to help smaller primes complete production. This is why it is hard to determine exactly which manufacturer’s parts should be on a particular Carbine.
There was also a transition period when improved parts were phased into production during late Summer 1943 to Fall 1944. Thus, the only Carbines with production parts you can be relatively confident in were manufactured between these dates. Determining the correct type of part for the production era of an M1 Carbine is one challenge; figuring the actual manufacturer of a part is another. Harrison’s book lists all known subs for each manufacturer and era of Carbine.
It is easier to identify the types and configuration of parts that should be on a Carbine based on its approximate production date. Our goal in restoring an M1 Carbine will be to determine what the correct configuration and type of parts are likely for certain production-era guns. Granted, this information cannot be guaranteed due to the transition period where improved parts were incorporated. Deciding which parts should be on an M1 Carbine comes down to probability rather than certainty.
Caution: Do not try to modify or place new markings on original parts. Such an effort is fraud! It is one thing to stamp a cartouche on a new stock that can be identified as a replica. It is another to modify markings on original parts and stocks.
This article series will result in the restoration of a Rock-Ola M1 Carbine, serial number 4629517, which has been determined to have been produced at the very end of Rock-Ola’s production contract in May 1944. It demonstrated to Guns & Ammo’s staff the care that must be taken when making decisions about the parts on a specific gun.
Dating an M1 Carbine
Generally, the manufacture date stamped on the barrel several inches behind the muzzle is a more accurate date of when the gun was assembled. G&A’s Rock-Ola features an Underwood barrel with a “5-44” date. Barrels were often installed on receivers soon after the barrel was produced because barrels were commonly the part that held up production. Usually, once the dated barrel was installed on a gun, the M1 Carbine was completed within a month or so. Use the receiver’s serial number to determine an approximate date and then refer to the barrel production date to refine the window of time. Once you have a close date, you can move on to determining the types of parts that should be on the gun. Note that some M1 Carbines had the barrel replaced after World War II and the Korean War.
All M1 Carbines that were retrofitted after World War II are believed to have been given an adjustable rear sight and a lever-type rotary safety, 30-round magazine and a front band featuring an integral bayonet lug. By and large, these parts were not original to an M1 Carbine when it was manufactured. However, this topic should be defined more than simply what manufacturers’ parts appeared on a gun. Again, there were periods when parts were transitioned to updated designs. Actual production would have mixed older parts with newer parts as bins were refilled and older parts remained at the bottom during the transition. Basically, it was “first in, last out.” Many researchers deserve credit for studying thousands of M1 Carbines and inspecting existing original records. The list of proper parts is based on what is known of original manufacturing records and probabilities. Absolutes are rare. This article will identify the visible external parts that should be on a Carbine, though it will not cover the entire topic of correct internal trigger parts, for example. We leave this to each reader and encourage additional research.
At the end of production for the smaller primes, and into the late Spring to Summer 1944, it is still uncertain as to which parts might be encountered on Inland and Winchester M1 Carbines. This was a transition period from early parts to upgraded parts such as four-rivet handguards, round-type instead of flat-type bolts, the Type B operating slide featuring an undercut bolt boss, and the Type B, wider front band without the bayonet lug. The Rock-Ola M1 Carbine used as this article’s restoration subject falls into this category and is an excellent example that demonstrates the need to carefully analyze what you have before simply replacing parts. Carbines at the end of production of the eight smaller primes can feature a mix of both part designs and manufacturers.
There are three types of stocks used on M1 Carbines: “High wood,” “low wood,” and “pot belly.” High wood was the original stock design. These stocks are identified by no wood removed in front of the receiver on the right side of the stock. The stock is the same height on either side in front of the receiver. With the handguard installed, only a small gap shows between the stock and handguard. These stocks also had a sling cut that looked like a capital “I” with the smaller bars on the top and bottom like a serif font. These stocks were the only stock used on all production examples into late 1943 and early 1944, other than the M1A1 stock. The M1A1 stock transitions from a high-wood forend to a low-wood forend during this same timeframe. The parts described here, and the era of use, also apply to the M1A1.
A low-wood stock has wood removed for a distance ahead of the receiver on the right side of the stock. The stock is not the same height on both sides ahead of the receiver. With the handguard installed, this stock will show a large gap between the stock and the handguard that shows nearly all of the operating slide. This stock had a sling cut that looked like a capital “I” without the serif-font-like bars at the top and bottom. These stocks began to appear in late 1943 to early 1944. Some were used during the late production of the eight smaller primes. Inland and Winchester used the low-wood stocks exclusively until around Spring 1944. Some later low-wood stocks had a small cut on the front-left side of the receiver, inletting for the selector switch of the M2 select-fire carbine.
The pot-belly stock was a post-war replacement that had a slight swell on the bottom of the stock in front of the triggerguard to the front band. This stock also had the M2 selector-switch cut and were designed to be stronger in support of full-auto operation.
There were two main types of handguards used: Two rivet and four rivet. There were several sub-types within these primary types, which had some subtle differences. The two-rivet was used on early-manufacture guns. The rivets were used to attach the metal band on the underside of the handguard that inserts into the front of the receiver. Only late-production examples from the eight smaller primes used the four-rivet handguard. Inland and Winchester transitioned to the four-rivet handguard by Spring 1944.
The original rear sight on the M1 Carbine was a two-position Type A “L”-shaped flip sight. It provided a zero of 150 and 300 yards. Inland provided hundreds of thousands of these L-sights to other primes. These sights were used exclusively into early 1944 and thereafter mixed with adjustable sights depending on what was available. There are many reproductions of the L sight in circulation. When originally installed, the L sights were not staked as the adjustable sights were. If you have a Carbine with an L sight, and there is a gap between the top of the receiver at the rear-sight dovetail and the base of the L sight, this is a sure sign that someone milled or filed the stake marks off the receiver and put an L sight on it. If the sight slot needed tightening for the L sight, a thin straight-line mark was struck across both sides of the sight slot, which looked as if it was done by a chisel.
Adjustable M1 sights first appeared in early 1944. By early 1945, only one-in-three Carbines produced by Inland and Winchester had an adjustable sight. There are two types of adjustable sights: Type “B,” milled, and Type “C,” stamped. They can be differentiated by what type of windage adjustment knob they have on the right side of the sight. The milled sights have a concave windage knob. The stamped sight has a flat windage knob. Both Inland and Winchester used the Type B sight until late in production and the Type A L flip sight when the adjustable sights were not available. Inland and Winchester began using Type C sights late in production. Saginaw S.G., Saginaw S’G’, National Postal Meter and Underwood only used the Type A sight. Quality Hardware used a few Type C sights at the end of production. Rock-Ola began using the Type C sight on the last two production blocks of guns above serial number 6,000,000, or about the last 50,000 rifles produced. Standard Products may have used the Type B sight late in production. IBM may have used both Type B and C sights in the late-production Carbines. The rear sight is an area of great uncertainty after early 1944. Look at wear patterns and stake marks.
The milled sight was used from early 1944 to the end of production. The stamped sights began to appear in late production Inland and Winchester M1 Carbines, and as replacement sights post-war. Almost all post-war adjustable sights were stamped. Adjustable sights were always staked to the receiver with a center punch, twice.
To Be Continued...
Part 2, featuring production information, descriptions of the safety types, bolts, trigger housings, barrels, operating slide, barrel bands, and front sights for the M1 Carbine, will be out tomorrow, followed shortly by part 3.
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