very nice pre ww1 rifle, good old times
my first thought when I read 57 was 8x57IR with Mauser A-Base rim.
something I look for!

DWM K(Karlsruhe) M 88A headstamp

also available in 7x57R

it seems the 8x57 IR A-Base was a left over from first german trials for a smokless 8mm cartridge in 1888

it need a scope again, something also pre ww1 on claw mount. if you come to germany with this rifle some day its no problem.