Assistance Confirming Suspected 1905M Factory Sporter Requested

[Bluenoser]

That be the one.
I was particularly struck by the similarity of the numbers on the barrel to that of my Ross. Both 4XXX range, same location, font and size, same inconsistent spacing and same increased space between third and fourth digits. Too many similarities to be a coincidence. The one on CGN also had a very good bore. The suggestion of a factory re-barrel is sounding more plausible, but I am having difficulty understanding why they would have also applied the assembly number to the new barrel.
It would be interesting to know how many similarly numbered 1905s at out there and what is known about them.