Rifleman Q&A: Two Serial Numbers On An M1 Carbine?

by
posted on April 30, 2021
** When you buy products through the links on our site, we may earn a commission that supports NRA's mission to protect, preserve and defend the Second Amendment. **
m1-carbine-national-firearm-museum-f.jpg
Q: I recently purchased a "G.I." M1 carbine. The only unusual aspect of the gun is that it has a serial number in the normal location (behind the rear sight), but the same serial number is also stamped in front of the rear sight. The two serial numbers appear to have been stamped at different times. Can you explain why the serial number was stamped on the gun twice?

A: Most M1 carbines were originally fitted with non-adjustable "L-type" rear sights. When they were arsenal rebuilt after World War II, regulations called for any superseded parts to be removed and updated components installed. One of these new components was the improved rear sight that was fully adjustable for windage and elevation.

When the new sight was retrofitted to some overhauled carbines, it could obscure all or part of the original serial number. In such instances, the serial number was re-stamped in front of the rear sight by ordnance personnel as part of the overhaul procedure in order to have the serial number visible. A carbine encountered today with two serial numbers has unquestionably been through an ­arsenal overhaul.
This Underwood Elliot Fisher M1 carbine in the NRA National Firearm Museum collection has the later ramped rear sight that partially obscures the serial number. On other models, the sight could obscure the serial number entirely, requiring arsenals to re-stamp the serial number elsewhere for easier visibility.
This Underwood Elliot Fisher M1 carbine in the NRA National Firearm Museum collection has the later ramped rear sight that partially obscures the serial number. On other models, the sight could obscure the serial number entirely, requiring arsenals to re-stamp the serial number elsewhere for easier visibility.

Most of the M1 carbines seen today have gone through extensive post-war arsenal overhauls. This resulted in many of the original factory parts being replaced by later pattern components, particularly the ramped rear sight and the "Type 3" barrel band with the integral bayonet lug. However, the re-stamped serial number wasn't standardized across all carbine rebuilds, so just because a particular carbine might only have one serial number stamp doesn't mean it hasn't gone through the rebuild process.

Additionally, the M1 Garands in U.S. military service underwent extensive rebuilding in the years following World War II, and there's a wealth of information on the markings and indicators found in rebuilt M1s. Bruce Canfield has a great overview in his story, "M1 Garand Rebuilds: History & Markings."


Latest

Magpul Hunter Lite Stock
Magpul Hunter Lite Stock

New for 2026: New Products from Magpul

Magpul announces new metal-magazines, new stocks and pistol frames.

New for 2026: Burris Veracity Riflescopes

The latest generation of Veracity scopes is available in a variety of 5X magnification ranges.

New for 2026: Springfield Armory 10-8 Performance Master Class 1911 Pistols

Springfield Armory and Lipseys have partnered to offer a highly custom 1911 with input from Hilton Yam.

New For 2026: Diamondback SDR-A

Following the release of its Self-Defense Revolver in 2024, Diamondback Firearms has now lightened its design and reduced the cost with the new-for-2026 SDR-A.

Rifleman Review: Walther Arms PDP F-Series 4-Inch

Walther Arms continues to expand its F-Series handgun line, a design initially developed for women but that has broad appeal across the firearm consumer market, thanks to its unique design elements and feature set.

Mossberg Expands Budget-Priced Maverick Line With Semi-Auto Model

As part of its International family of shotguns, Mossberg announced the introduction of the Maverick SA Semi-Auto, a versatile, value-focused semi-automatic platform built to deliver reliable performance.

Interests



Get the best of American Rifleman delivered to your inbox.