When was Smith-Corona 1903A3 serial number 3639763 made?

With the serial number that you have supplied,your Smith-corona model 1903A3 was made in the year 1943.these rifles were only made in the years 1943-1944.If your rifle has a letter C prefix to the serial number,then this indicates that remington also made a model 1903A3 with the same serial number. These were the only 2 manufactures of the 1903A3 rifles.