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The serial table says one year, a stamp on the gun says another

The table and the gun disagree

This is the most common form of the discrepancy, and the most misunderstood: nothing is wrong with either number. A maker can stamp a date on a component and keep a separate serial ledger, and the two do not have to agree — one records when a part was made, the other when the firearm was assembled and logged.

A real case

From the record

A Remington M1917 whose owner found that a serial lookup gave an 1918 October production date, while the numbers stamped on top of the barrel behind the front sight — which on that rifle record the month and the year — read August 1918. Two months apart, both factory marks, no forgery involved.

What actually produces the discrepancy

On Remington arms made after 1921 the barrel carries a date code on its left side near the frame, recording the year and the month, while the serial numbers live in a separate factory record book. Two independent records of two different events. Reading one as the other produces a discrepancy that looks like an error and is not.

What to watch for

The Remington Society states plainly that dating a rifle from its barrel code is reliable because the company rarely changed barrels on a customer’s rifle — but that using barrel codes to date a shotgun is "somewhat unreliable, as shotgun barrels are often interchanged at random". On a shotgun the barrel code may describe a barrel that was fitted years later.

What to do about it

Working with this cause
  • Decide which question you are actually asking. "When was this part made?" and "when was this firearm made?" have different answers and different sources.
  • Find every date-bearing stamp on the gun, not the first one. Barrel, frame, trigger guard, under the stock. List them all before trying to reconcile them.
  • Treat a two-month gap as normal on a mass-produced arm. Treat a multi-year gap as a signal to look for something else — a replacement part, a rebuild, or a stamp you have misread.
  • On a shotgun in particular, do not date the gun from a barrel code alone.

Sources for this page: Remington Society of America — manufacture dates, serial numbers by date, and barrel date codes · Remington — United States Rifle, Caliber .30, Model of 1917 (manufacturer document).

Other reasons two sources disagree

The published table is known to be impreciseThe maker’s own lookup returns two yearsThe numbers are not in the order you assumeThere is nothing left to checkThe number on the gun is not the original one
The lookup shows its working

Every result names the chart it came from, the threshold it rests on, and — where the published table is documented as imprecise — says so on the result itself rather than returning a bare year.

Open the serial number lookup All the causes

Compiled and sources last checked 2026-10-14. This page explains a documented discrepancy; it does not date your firearm.