Hi Craig. Again apologies for not getting back to you with your report on your rifle's details. I will get onto it.

In a lot of cases, the serial number on the barrel is almost totally obscured by the front scope base. They were not re numbered. There was a standing order that the HT rifles were not to be stripped with any other rifles on the bench so to ensure there would be no mixing of parts. To this end, the small parts were not required to be numbered, but a lot were. Barrel manufacture dates were usually close to the build date, but exceptions found are where H rifles or rifle club rifles handed in retained their barrels after passing gauging and accuracy testing. Have even seen a few matching foreends retained. The rest of the parts were gauged as well, and those that passed were stored and used in the assembly of completed HT's. One good example of this is a rifle with a nosecap serial number struck through (not matching) showing it had come off another rifle and hadn't been renumbered. The struck through number is also on the list of HT serial numbers, so it had come off one rifle at conversion and used on another.

Not sure about the punch mark under the serial on the barrel. Maybe a pic will give some clues.... Will PM my email to you,
Cheers,
Brad