In the Belgian system of proof the individual inspecting the gun would stamp his (or her?) own inspector code - "controller of proof" ID as PeteM mentions. This code is in the form of a star over a letter, in this case star-over-V which, by Pete's reference, was "Isidor Maçon, who was a controller from 1929 to 1953".

The "v" is not a date code, it is "star-over-V" an inspector's ID code.