Is this an ink stamp or stamped into the metal ? Only hoops I've ever seen w/ a number was on Yamaha cast hoops. (Upload some in focus pictures of the hoop & ears, ... this could provide a better clue).

I've seen a few rims with names and/or Social security numbers hand engraved in them as an apparent theft deterrent or means to identify the drum if it were stolen (although how hard is it for a thief to remove a hoop and pitch it?).

I've never seen an actual stamp like you've pictured. Does that number match the serial number of the drum? I don't see much purpose for a drum company to devote the time and labor to doing this as hoops are mass produced generic parts. Maybe a "boutique" builder would take the time to do so although, again, I don't see a reason for it.

If it doesn't match then I would guess other possibilities might be that is the part number for that particular size of hoop or some type of inventory number if it belonged to a school or similar organization.

Even if it does match the serial it could have possibly have been stamped there later by an anal retentive owner or a school district to insure that the original hoop stayed with the drum it came on.