Im kinda the same with my 308 weatherby vanguard (re branded howa) in that I shoot 5 shot groups and I seem to get 3 in a tight group then half inch over I get 2 holes in a tight group. Its a deer rifle and shoots 5 into 1-1.3" at 100 yards with cheap speer 150gr hot cors so Im not complaining just kinda confused I guess.
That's probably the answer to your own question of confusion. Try a different bullets.shoots 5 into 1-1.3" at 100 yards with cheap speer 150gr hot cors so Im not complaining just kinda confused I guess.
It's also worth noting that the older generation of gunsmiths would commonly bed a section of the barrel out in front of the recoil lug on guns that had this phenomenon and most often that would correct it. Where as todays smiths leave everything free float.
Dan