So you mounted these before but never shot with them, correct? As mentioned, the cant in your inserts might account for 1-2 MOA if that.
Lightly applying a lubricant to the Picatinny rail on the gun, the bottom of the ring bases, or the steel clamps that secure the ring base to the rail can help the ring slide into natural alignment rather than sticking as you tighten the base screws.
I install the ring bases to the gun. Place bottom inserts into the mounted rings, scope into those inserts. Adjust eye relief and rough level. Install the top inserts into the top of the ring caps and place them gently over the scope and press down toward the ring base. Use a methodical cross pattern for tightening while keeping an eye on levelness. It is tedious, but I’ve mounted dozens this way and have it down to a few minute process.
Last note that I’ve mentioned in other Burris ring threads, some rings are just poorly machined. Most of mine have been good, but I have a 30mm set that requires almost 15MOA of windage correction to center the scope. If you have the time and curiosity, try switching rings front to back or rotate each one 180 degrees in place and observe what happens to your point of impact. Good luck.