Sounds like a reason to get a bore scope
Bore scope's are alright, the one I've got is buried in a box somewhere,
Used correctly It'll get you on paper, but fine tune zero still got to put some rounds down range.
Know several that bought rifle & scope then had the shop mount scope & bore sight and thought it was zeroed poa, and it wasn't.
the armorer that mounted & bore sighted probably told them rifle needed to be shot & zeroed poa and they didn't listen.
Course you can always do like I & most others have done & still do. Mostly because I'd never even heard of a bore scope till I read article in American rifleman or some magazine.
I mount scope, the put rifle into my homemade sled on bench, remove bolt,
put target 25yrds, adjust feet on sled to see target through bore, then adjust windage & elevation on scope to target,
Then move target to 50yards and do same.
Then move target to 100 yards then shoot & fine tune to zero.
Course theres the little laser bore sight tool too. Never used one, but seen it done.
It chambers in rifle shoots laser through bore onto target then you adjust windage & elevation on scope to poi.