your pistol was made by colt in 1918. you are probably reading 'remibgton rand' off the slide. It is not unusual to have the wrong slide on a colt pistol. this happends when a number of 45's are broken down for cleaning and parts are mixed when put together.
1920
I checked www.oldguns.net and they show the manufacture date of Remington 1903A3 serial no. 3851292 as 1942.
RW isn't part of the serial no, it stands for Remington Works 1915
That is not a serial no of a Remington 1911A1 they stopped in 1945 with 2465139.
1914
1913
1920
1919
late 1919
1920
1915
1912