I’ve just acquired a 11x60R Mauser cartridge and I’m trying to ID the manufacturer. As shown below, there is what appears to be an S at 9 o’clock and an A at 3 o’clock. There may be another S at 12 o’clock but it is different to the first one. The number at 6 o’clock is either 75 or 76.
I don’t think that the two circles are part of the headstamp but I could be wrong! Any help is greatly appreciated.