Hello kuduae,
Thanks for the reply.

I was suspecting that was the standard marking for an 8x57. I sure hope that it turns out that the barrel was replaced or rebored by Johann Peterlongo,
to some kind of an 11mm caliber. Perhaps a 10.75x68, or an 11.2x60 or an 11.2x72? Otherwise I paid a "very high" price for an ordinary 8x57 sporter.
I guess I'll have to wait to see what I bought. Thanks again.