The methylene chloride that I soaked the lid in to remove the Duck tape must have removed most of the ink, but under magnification I could just see traces of red ink in the boxes marked .177 and .22. The same on the opposite edge of the lid. Always something new to learn!

So it looks like the owner decided to buy a BB barrel as an extra. I suppose he could also have used it for darts, not wanting to ruin a rifled barrel..