BSA mystery Supersport without serial number

[mrto]

Thanks for the input. That would make sense in the UK, but over here in Norway, buying and changing barrels on old sporting airguns is something done by very few.
Plus the gun seems totally untouched by tools after it left the factory, so I'm having a hard time accepting that the gun has been worked on.

You could always try contacting BSA and ask them,in my experience they are quite friendly and helpful.