Springfield Armory Inc (SAI) has been confusing people with this for decades.The US Government Springfield Armory, and the commercial Springfield Armory Incorporated, are not related at all.
For reference, production of M14 rifles for the military started around 1959 and ended around 1964. Your # is dated by it's assembly date at Springfield Armory, first in Texas, now in Genesio, (spelling) IL. They are considered machine guns and must be transferred as such, using the appropriate local and BATF approvals. It was mated to some USGI M14 parts that were surplus back in the early 1990's.The US Government operated a weapons arsenal called Springfield Armory (or Springfield Arsenal, depending on who you talk to...) The US Government Springfield Armory built guns for the US military for a looong time, something like 150 years or more.The US Government Springfield Armory was in charge of the design, prototypes, and early production of the M14 rifle for the military.The serial number listings by month presented below were developed by Scott Duff, a recognized authority on and author of a series of books on the M1 Garand.The following information can be found in the books "The M1 Garand: WWII" and "The M1 Garand Serial Numbers and Data Sheets" found at Fulton Armory, and are used here with Mr. The following information is copyrighted and may not be copied, distributed or used in any other forms of publications, or in any other written or electronic form without the expressed permission of Scott Duff or No monthly range of serial numbers has yet been developed for Post-World War II production of the M1 Garand.