if its greek why did they mark it 7.91 but at the same time remove all the other markings
this CRD barrel I have still has the british proof marks and a serial number

From what you have said, CRD is Climax Rock Drill from Redruth in Cornwall who made .303" Mk2 Bren barrels and T-3884 is a Daimler Mk2 Bren of 1942/43
now that information fits the barrel I have

so what happened to it?
the whole gun then went to war was lost by the brits and then who ever found it made it into 8mm? I say this because of the lack of stampings on the barrel. every 303 barrel I have is numbered renumbered reproofed with numberes lined out but this one is basicaly clean but its not scrubbed beacuse the original proofs are still perfect

what do I need to do to my 303 MK2 bren to make it work with this barrel?
whats the barrel worth?
thanks