That’s the laser engraving on the PacNor barrel that was put on a Ruger No. 3 receiver. It appears that the latest in nomenclature is to call No. 3s that have been rebarreled or restocked or both, Ruger No. 2s. I suspect pretentiousness, but the truth is that it facilitates written communication.
Wander over to the page under the RELOADING tab and have a look. Here’s the link: https://paulskvorc.com/ruger-no-2-chambered-in-416x-348-winchester/