You asked me and others a question.
You got my answer!
As a professional shooter I wore out a barrel every year for a lot of years.
I very much doubt that you or anyone else on this forum would shoot 6000 rounds per year as I have done.
A bad tradesman always blames his tools.I would not touch anything newer than a 461 or 579.
You COULDNT give me a model 75 or 85.

2 more things that come to mind:-
How is the trigger gaurd and floor plate assembly fixed to your rifles??????????????????????????
Having observed a hunter in the Territory loose a magazine out of his rifle without noticing it is another problem for the 75 and 85 and those magazines are worth about $150 each.
You are talking through your arse if you are trying to tell me there is no difference between the bolt faces on the new and older models.
And one more thing iff you are such an authority on SAKO why did you ask the question in the first place????????????