I checked with the Remington Collector Society posting for 1903a3 on our forum site and it indicates a receiver date of aproximatly October of 1943. I beleive would correspond with the barrel dated a month prior. I remember reading a post from Rick the librarian indicating barrels can at times precede receiver dates by a couple of months. But as always I defer to those who may have more info. from another site that they can direct me to.
Thanks for comments.