Ammo verification. Headstamp x * - 1 50.

Hey bought some ammo from a old guy he sold me a good amount of 54rimmed but threw in a few boxes of unrimmed ammo and I can’t find the head stamp online. If I had to guess 8mm Mauser cause it’s bigger then .308 and about the size of the 54r. Headstamp is x * - 1 50. If anyone knows or has it let me know I know it’s some older military ammo from the tarnish but I’ve got 4 boxes of it.