this was once a fine suhl made mauser sold by Emil Adam (have an old box 8x57IR with mauser a base rim) in berlin, than falling in the hands of someone ruthless https://www.lauritz.com/da/auktion/emil-adam-berlin-jagtriffel-kal-6-5-284/i5598672/
who change it into a 6,5-284 froim probably 6,5x57, take the claw mount of and the iron sights ...
the world could be a bad place sometimes, dont wish him good luck