CnR collector, your rifle just taught me something.......All of the A?-four digit 4T rifles I've ever seen have been 1943 dated. I had assumed that the adoption of the 5 digit serial commencing with a '3' started at the very outset of 1944..... (& indeed I still am pretty certain it commenced very early on in 1944) but your rifle has a '1943 mfr serial number' yet is clearly dated 1944, so there must have been a little run-over. Like you said nunquam narro nunquam!
ATB