Had the same thing the other day.
I cleaned out under the action and barrel channel the other day and went out and checked some different primers and had two close and one two inches away.
So went back to the fed primers i was using and went out to muck around with the seating depth and same thing and even my accurate load was playing up.
Puzzled i went back home and started checking nuts and bolts and then thought that barrel channel had a lot of clearance.
Yep fucked up putting it back together and the lug wasnt seated properly from the cleaning session.
The young fella went out and shot a deer at 583y a day later!
Lesson learned check and double check
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