This is a custom stainless-steel barrel chambered in .257 Weatherby Magnum - probably. The only indication of the chambering is a transparent sticker. It is definitely chambered for a belted magnum cartridge and the bore appears to be .257". It is 24" long and measures 0.700" at the muzzle.
Bore - 9/10 - The bore has a little throat erosion but no other notable wear or defects. Borescope verified.
We use the NRA Modern Gun Condition Standards Grading System for grading part conditions. You can read about it HERE
