Barrel Markings on DH?

[Dean Romig]

In order to add choke to a finished set of barrels they must be "jug choked" or "back bored" resulting in barrels that have been "over bored".

[Autumn Daze]

Steve, My thoughts are that the barrels were sent back to the barrel dept. to be back bored for more choke constriction. The + sign might be added to inform future employees that these barrels have larger than nominal bores. Or.....the tubes could have been bored oversize during the original barrel boring operation and this is a stamp to indicate that.

Maybe I should start a new thread asking members to measure the bores of guns they have with the + sign to find out if my thinking is on track or just BS.