[DonVoigt]

Third party inspeciton marking? Maybe Finland or ??? , inspected and approved/repaired before refinishing.

I've looked in all (both) marking reference books I have, and the closest is a Finn marking, of a T in a circle and later two "L" lookingmarks, but upside down and facing with the short leg away from each other. I know, clear as mud and very helpful.

Rich,
agree, could be a hammer- Thor's hammer- maybe one of the Nordic countries.

All just my pure speculation at this time.

I think not the original barrel, as it has no bore diameter designation.