The mark [ *s ] was used by controller of proof Daenen Charles from 1952 - 1968. This gives you a basic time range. There should be a date code on the front right side of the trigger guard, a number in a partial box. A similar date code can be found on some other parts. In 1950 (only) the date code was on the front left trigger guard where, on this pistol, someone has etched a name or something...
Without being able to see/examine the front right trigger guard or marks on various parts, it is difficult to determine the year of production. Because of the dates Mr Charles used the mark *S you can guess it it from 1952 or later, but not much later. I have seen pictures of a 1952 pistol with sr# 56, 600. My 1950 pistol is sr# 28,900. The pistol pictured is then likely from early 1952.
A photo of mine is attached for reference for date code and controller of proof code. A PDF with info re other marks is also attached. Hope these help!
Green Circles = Controller of Proof
Yellow Circle = Date Code
* This date code indicates 4th quarter of 1950
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