May be wrong here and I am in no way decrying the gun as it looks to be in an overall good state , but has it been re-colour hardened at some time ? My first impression would be yes .The action and plates look too good for the gaped screw heads .
Were the plugs in the stock original ? I have seen old guns with similar "repairs" that were done from new , both to replace knots and to fill shakes or voids in the wood that did not show up till the stock was being turned out . The fact that the colour match is so good would in my mind say it was from new as to get that match years later is very difficult . Though I do suspect that the small plugs were later to keep the originals in lace .
One thing that is obvious from the photos is that the barrel flats appear to be are hard down on the action on one side and that the extractor stop pin is hitting the action bridge . This needs to be eased off as it will have an effect on the locking bolt and can lead to the gun eventually blowing of face .
