What caliber is this cartridge,please?

I found this in a box of old 8mm Mauser ammo. The bullet measures 8.30mm and the casing is 59mm long. Head stamp is " BPD at 12:00 o’clock, “36” at 6 o’clock. The primer has a read annulus around it.

It is an 8x59RB Breda, an Italian MG round. Yours is fairly early and a bit scarce as a variation without the base groove.
You should probably repost this on the Discussion Forum, and not the Buy/Sell/Trade Forum.

Thank you for the reply. I posted the question by mistake and cannot move it,sorry.