Ok, I'll throw out other possibilities. It appears you have 2 groups going on. That suggests maybe action screws loose, bedding or free float, parallax error or simply how you are with your bench set up.
"Secondary recoil lugs" means anything other than your recoil lug is interfering with grouping.
It could be screws, triggers, bottom metal/mag box or other things.
Check the easy stuff first then have a buddy shoot it with you.
So, if it were mine, I'd remove the stock and just start looking around for shiny or off color rubbing signs anywhere in the stock including the barrel channel. 30 minutes looking around. Check your screw holes in stock and the action to make sure those are centered visually.
Put it back together, torque it and reassess.
Next trip, look for parallax before shooting and you and your buddy shoot 2 groups after fouling.
Good luck. Your rifle has potential....