Send me the two or three letter code on the left side of the barrel back by the receiver then I can tell you the month & year of manufacture. You'll need a magnifier.
Your Remington model 1903 was made in the year 1941,with the serial number that you have provided.
It was in production from 1931 to 1949, when it was superseded by the Remington 870.
1959-1962
your Remington model 512 was made from 1940-1962,with a total production of 395,000 guns.
With the serial number that you have supplied,your Remington model 1903 rifle was made in the year 1941.
1930'S
1912
The Model 1100 has been made since 1963 and is still in Remington's catalog.
Check the manufactured date link on the Remington Society of America for details.
Second year production 1906.
The last year of production for the Remington model nylon model 66 was 1990.These rifles were made from 1959-1990 with a total production of 1,050,336.
they were made from 1941-1970, they are date code (month/year) stamped on the barrel, diagram for location and table on Remington Society of America.