I think you'll need more drastic action, you mentioned to me that one of the front legs had 'sprung' which suggests that your stock isn't/wasn't stable and being able to change the POI by adjusting the tension on the bolt by the trigger guard supports the view that the stock has warped. Re-inletting the stock may fix the problem but may not be a permanent cure if the instability persists and won't resolve any problems caused by the sprung leg. I'd re-inlet, but it may be time to consider a new stock.... You've invested time and money in tuning the HW and a decent scope, but the stock is what's letting you down IMO.
I can't shoot my ProSport to the level you shoot your HW but it's never, ever shifted. My Ginb stock is a comfortable interference fit at all points and I only need to pinch the bolts, the tightness is not in the slightest bit critical so long as they've got some tension on them so I'm convinced the stock is your problem. No need for locktite in my tool kit!
Ask Helen what to do, and then do the opposite. I suspect her advice on this matter may not be entirely objective/helpful at this time
Yay, go Helen!!
ISP Airstream MK III No 15 which is a bit poorly at the moment and having a rest
AA Pro Sport + Ginb FT8 stock + Bushnell 4200 6-24x
EV2 MK1 + Leupold Comp 40x
Weihrauch HW100 KT laminate
SBFTC Competition Secretary