The Turks were not building any .257 Roberts rifles, not even if you called it 6.35x57.
What happened was that the Turks brought all their rifles to the same caliber, 8mm, and as near the same configuration as possible in and after 1933. Then a few years ago they dumped thousands of obsolete bolt action rifles on the American market, always hungry for something cheap to plink with.
Yours is one of those surplus rifles that has been sporterized.
It has had a .257 barrel installed, the action drilled and tapped for scope mount, and no doubt the bolt handle bent to clear, then buffed out and reblued. Hopefully it got a low scope safety and maybe even an adjustable trigger.
The stock has a nice gloss, I assume it is a conventional sporter style replacement, not the old military wood.
I haven't a clue as to what the oriental chicken tracks signify.
There is a site devoted to the Turkish Mauser but he doesn't translate, either.