That sn is from a block that was given to the Inland Division of General Motors Coporation. Inland made @ 43% of the total M1 Carbines made. There should be a date on the barrel. What are the markings on the bbl and receiver? If you are asking was it used overseas, the short answer is that it's not easy to find out.
what year was my Winchester M1 carbine serial number 1210906 manufactured
With the serial number that you provided,your Springfield model 1873 Trapdoor Carbine was produced in the year 1877.
Universals are a civilian version of the M1 carbine, made after WW 2. No serial number data is available for the civilian carbines- sorry.
By posting a question here with the maker's name and serial number- IF it is a military issue carbine.
The Colt AR-15 Carbine with the serial number SP 212104 was manufactured in 1991. Colt's serial number system indicates that the "SP" prefix corresponds to rifles produced during that year. For precise information, it is always advisable to consult Colt's official records or a firearms expert.
$500
It was a manufacturing code.
Behind the rear sights on the receiver.
July 1944
It depends on the actual serial number.
About Jan 1944.
made in 1888