The U.S. Carbine Caliber .30

U.S. Army Ordnance
Serial Number Assignments

Understanding Serial Numbers - Understanding Dates of Manufacture

Dating a carbine by its serial number alone is difficult and not always accurate given the circumstances inherent with manufacturing and the logistics situation during the time the carbines were manufactured. Some people estimate a carbine's date of manufacture by adding the quantities manufactured month to month to the assigned serial number blocks. This is not an accurate means of estimating the date the carbine was finally assembled or when it passed its final inspection.

Serial number blocks were assigned by the Ordnance Department on an as needed basis, generally in response to the awarding of a contract to a given manufacturer. Think of each serial number block as a separate contract. Contracts had a completion date but there was no requirement for completing one contract before starting another. There was no requirement as to using the serial numbers in order.

A few manufacturers used some serial number blocks out of order. Some of these blocks were split up and used before or after other blocks. Some manufacturers used more than one block in the same time frame.

A few of the manufacturers used subcontractors to manufacture their receivers. One manufacturer separated out smaller blocks of serial numbers for use by subcontractors who would use these serial numbers concurrent to receivers being made by the prime contractor and/or other subcontractors assigned lower or higher serial number blocks.

The serial number was placed on the carbine receiver during the manufacturing process of the receiver, not when the carbine was finally assembled. The decision for which receivers would be used for the U.S. Carbine Models M1 or M1A1, and some of the M2's, were made well after the receiver was completed as all of these models used the same receiver.

Serial numbered receivers that failed to pass inspection were set aside as rejects if the defect(s) could not be brought up to minimum standards. As solutions to old problems were learned, some of the same receivers were brought back online and completed (i.e. Inland receivers initially rejected because of an off spec deep hole drilled for the recoil spring and guide, later recovered and altered to use a detachable main spring housing). If a receiver was scrapped and not used, its serial number may or may not have been reused.

No documentation from Ordnance, or any of the prime contractors, has been found that indicates the date and serial number of carbines as they were assembled or when they passed final inspection. Given the high volume of production, receivers were generally assembled as part of a carbine within a few months after the receiver was serial numbered.

Barrels were a critical component in the production lines. If inventory ran out it could shut down production. Four of the prime contractors did not have the ability to manufacture barrels. The ebb and flow of mass production created parts surpluses and shortages for all the prime contractors, barrels included. Shortages were common until Ordnance arranged for additional barrel manufacturers.

During the first half of production the barrels were often mounted on a receiver within 1-2 months of when the barrel was made. If a receiver has its original barrel and the barrel includes a date, it may provide a general idea of when the barrel was attached to the receiver.

As time goes on more and more carbines are having parts replaced. Parts wear out, carbines are disassembled for the sale of the parts individually. Carbines have been, and still are, rebuilt from spare parts. Many people have reconstructed many carbines with what they believe should have been on the carbine when it left the factory.

U.S. Caliber .30 Carbine
Models M1, M1A1 and M2

Rather than assume the documents were followed to the letter, the serial numbers in tables C-F are presented with the lowest and highest reported to date. We would like to encourage you to share information you may have that will help reconstruct what was actually done versus planned. If you choose to do so please contact us using the forum.

TABLE C

Subcontracted Receivers

(also see Table E)

TABLE D

Leftover Receivers used by Winchester

- Underwood receivers that had not yet been hardened:

Winchester removed the Underwood name and serial number, then replaced them with the Winchester name and serial number.

- Receivers that retained the Underwood name:

Winchester sometimes lined out the Underwood name, sometimes not.

Winchester added the letters W A or A W to the bevel of the receiver.

- If the receiver had an Underwood subcontractor code, the subtractor code was left in place between the W A or A W.
- One or both of the letters of the W A or A W code may be difficult to see. Some have been reported with only one of the
two letters or in combination with an Underwood subcontractor code.

- The significance of the letter A is unclear.

TABLE E

Transferred Receivers

TABLE F

Serial Numbers Duplicated

(including use of X Suffix)

TABLE G

Irwin-Pedersen, Grand Rapids, & Saginaw

Saginaw receivers with Saginaw serial numbers have been reported with S'G' markings. At least one document has been found that indicates Saginaw received Ordnance authorization to sent an unknown quantity of receivers to Grand Rapids. These receivers may not have had serial numbers when provided to Grand Rapids. The Grand Rapids facility stopped carbine production on 01 Jan 1944 but continued to make receivers and trigger housings which were sent to the Saginaw Plant for assembly.

TABLE H

Inland Manufacturing
Engineering & Presentation Gift Serial Numbers

Inland later decided to present carbines as gifts to Inland employees, subcontractors, suppliers, members of the military or government, and others to show appreciation for their assistance and cooperation with Inlands war effort. The serial numbers allocated to these carbines were as follows.

The carbines used for this purpose were not from inventory submitted to or accepted by the government. Many were constructed using whatever parts were available. Examples being outdated parts and prototype parts that had accumulated throughout the various departments within Inland over the years of production. This included a few of the previous Engineering carbines no longer needed.

Carbines that have one of these serial numbers may be an Engineering prototype, a 'presentation' carbine, or both. They are a specialty that requires each be assessed individually to determine its historical significance. They should not be altered or fired. Doing so may alter their historical value.

TABLE I

Carbines with a Serial Number above 8 million

Incredimail 2 5 license key. The new serial number was hand stamped on top of the receiver behind the rear sight, in the vicinity of the prior serial number.