This is a common issue with factory barrel nut rifles. However the Burris inserts will get you where you want to be.
There are several causes for this including; bore curvature, and misaligned scope base screw holes. The biggest contributor that I have witnessed is the "stamped" recoil lugs and barrel thread "fit". The stamped lugs are not flat nor parallel side to side. Combine this with a loose thread fit and the torque on the barrel nut will force the barrel to seek its home in any random direction. This is often noticed with the barrel not parallel in the barrel channel.
Combine this misalignment with an excessive bore curvature and there have been instances where the rifle cannot be zeroed.
Clocking curvature while maintaining optimum headspace is a pita with a nut barrel. I've done it several times but requires two or more installs.
If saami headspace tolerance is acceptable near 12:00 clocking can usually be achieved 50% of the time just by adjusting the recoil lug thickness.

The Burris mounts are a good answer in most cases.

Good luck.