I've got a three year old hw97 that I've not had any problems with.
About nine months ago I fancied getting another one with the blue laminate stock,and this one has the same problem ,a shift in poi up or down,usually about 10_15mm at 30 yards.
At first I thought it was a problem with the action,so as a temporary fix I put the action from my older gun (which I know is fine) into the laminate stock, while I tried to figure out what the problem was.
To my surprise the problem was still there,so I was a bit baffled to say the least.
So I tried a different scope and that made no difference.
I took both actions apart but as far as I could see everything was fine.
I know that PC P's can have issues in the relationship between stock and action but I've never heard
this about springers but as a bit of an experiment I thought I would put the newer action in the older stock, and yes you guessed it the shifts have stopped.
Now I'm no expert so I'm afraid I can't tell you how this makes any difference but the only difference between the two stocks is the older stock is a tighter fit than the blue laminate one,I have to push the forend apart to drop the action in whereas with laminate stock it just drops in.
Hope this helps in some way.