I have an unmarked M700 bbl from an ex-police sniper rifle. (Bore, very good, 0-1 throat erosion.) Knuckleheads took them to the range and did not clean afterwards. They changed all of the barrels. I hand picked this one for a potential build. My guess is a Lothar-Walther. It is 26"x.90". Trade for AK or AR parts, especially AK-74 24mm Front sight base and brake.