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 When they were arsenal rebuilt after World War II, regulations called for any superseded parts to be removed and updated components installed.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

Dead Air Rxd910ti Suppressor F
Dead Air Rxd910ti Suppressor F

"9 mm Optimized, But 10 mm Capable:" Dead Air's New RXD910Ti Suppressor

The new Dead Air RXD910Ti harnesses the technology of the patented Triskelion baffle system to make for a 9 mm-optimized silencer that is also capable for use with 10 mm pistol cartridges and more.

Revisiting A World War II Marine’s Story

Secretary of War Pete Hegseth, in his speech to 800 assembled generals, admirals and senior enlisted at Quantico, Va., on Sept. 30, 2025, quoted Eugene Sledge from his timeless classic With The Old Breed published in 1981.

Review: Leupold Rendezvous Soft Cases

Looking for something better than a cheap nylon bag, but don’t need it armored for air travel? Leupold has you covered.

Preview: Hiperfire Hipertrain

Hiperfire’s Hipertrain is a cast aluminum housing into which the AR-style trigger system, safety selectors and pistol grip of the user’s choice (none of which are included) can be installed to create a trigger demonstrator/dry-fire trainer

New For 2026: Kimber 2K11 Comp

Kimber increased its 2K11 product line with the addition of two models with single-port compensators.

AR-15 vs. Bullpup Rifles: Which One Is Right For You?

Though bullpup-style rifle designs have become popular elsewhere in the world, they aren't nearly as popular with the American shooting public as the ubiquitous AR-15.

Interests



Get the best of American Rifleman delivered to your inbox.