Finnish Sako catalogue from 2002 lists muzzle thread as an option for P94S rimfires and as standard for TRG-22/42 only. So I don't think so. Though, even back then it was possible to send the rifle to the factory for all kinds of custom jobs, including muzzle threading, but I would not expect that to happen too often from outside of Finland.
For a rifle in the UK one clue of aftermarket modifications might be if there is an UK proof mark stamped on the rifle anywhere. Factory original would only have the Finnish proof marks (head of a lion wearing a crown). I have seen the UK proof mark stamped on the barrel near the muzzle thread and a lot of the times (maybe every time) the proof house had stamped the receiver and bolt as well.[quote[
it just looked to dark for a after thread as this would normally show the thread cut in nice clean shinny threads ?
bob.