I don’t know anything about this caliber, but I doubt that this headstamp’s year marking is legitimate. I believe the date and headstamp to be spurious and made for clandestine reasons. It is highly similar to some Israeli 9 rounds headstamp “S 1 44” and “S 1 49,” probably made in 1954 and 1959 respectively, in format and letter style. There was also a Portuguese round with a similar headstamp, although I forget it now (I had a fired case I found on a range, but it is or was in the Wooden collection - I gave it to Bill). It has a brass primer cup and bright green primer seal as I recall.
Maybe someone more familiar with this caliber of ammunition can tell us for sure what it is.
The case color is from a case-cleaning agent, either the product Case-Brite, or something chemically similar that puts that dull, almost gold color to the case. Very characteristic of Case-Brite, but there may be others.