The meaning of this A is not known but of the 27 that have the A, 18 of these are known to have been sold to a law enforcement agency.

Of the 43 carbines recorded between 001 andġ500, 27 have the A, 1 has the P, and 15 have no letter after the numbers. When production reached Z999 the serial numbers started over at 001 without the letter prefix, running numerically through end of production in 1978.Īmongst the first 1500 numerical serial numbers the letter A was sometimes added after the numbers and in at least one instance the letter P was observed instead of the A. Markings and their location are discussed in detail on the pages devoted to Carbines, Parts, & Markings. On top of the receiver behind the rear sight above the letters PMC. The exception being first half of the G series, which have the serial number Serial numbers were consistently at the front of the left side of the receiver above the stock line. So far, no carbines have been found that start with the letters I or Q. Ran alphabetically then numerically, when 999 was reached the next serial number started at the next letter and again ran 001-999. Serial numbers started with the Millville Ordnance and H&S carbines were continued into the Plainfield carbines and consisted of a letter followed by three numbers. The distance between each digit often varies. Serial numbers were hand stamped one digit at a time and are often not aligned with one another horizontally and/or vertically. The serial numbers used by Plainfield Machine followed a consistent pattern throughout production 1962-1978.

* Production may have started at A001 or A100 Carbines are presented in four different sections, each consisting of one or more pages. Post WWII Commercially Manufactured M1 Carbines (U.S.A.)

M1 carbine serial number lookup