pete this may not apply to your rifle but when my barrel started to dye it started throwing a shot out to the right say a 1/4 to 1/2 inch.
not allways but often and i blamed myself,bedding,scope,missed condition ect. but it continued to throw a shot horizontal to the right enough for there to be a problem
that wasent me, bore scope inspection showed first inch to inch and a half of the throat all fire cracked and holding carbon, very good scrubing(very good). shot a few fair
groups but not like it use to. so my barrel died. so just saying possible barrel..could do it.