This is a used Swiss Schmidt-Rubin K31 barrel. The caliber is 7.5 x 55mm. This barrel is in very good condition, with most of the bluing still in place. There are no deep scratches on it. The threads at the end of the barrel are clean with no burrs or mars. The rifling appears to be very clean. There are some proof style markings on the rear end of the barrel, near the threading. Please call for a description of these markings.