This is a Proto UL barrel back in .688 bore with Autococker threading — the two-piece UL system was one of the best mid-range barrels Proto put out. The body is dust silver anodized aluminum with the classic slanted Proto script engraved on the side. The Autococker thread stub is clean with no visible cross-threading or damage, and the o-ring at the junction is present. There is light use wear on the anodize but nothing structural — this is a solid, functional barrel back ready to pair with any UL front.
