The electro penned serial numbers were used on wartime production BSA No.4 service rifles. I just went and looked at a 1944 I still have that sports it's original blue finish and it's done just the same. I once had a 1945 that was absolutely mint and unaltered and it was the same. The serial numbers of the No.4T conversions are stamped and not electro penciled. I still have one virtually new 1945 V prefix rifle and it's stamped as is my very well used and heavily FTR'd ZF 1943 rifle that's had four scopes in it's career. Little details I never thought about!