Back to basics, did you shoot another group back at 100 after the 450 attempt?
Step one: check for obvious loose screws in scope mounts, loose suppressor/muzzle brake, action screws.
Step two, shoot 5 rounds at 100 yards with the turret at zero. If that group is good (1.5ish or less), and centered, proceed.
Step three, shoot 5 rounds at 300 (or 450 or whatever), scope still at zero do not dial a correction.. You'll need a decent size piece of cardboard for this if you're at 450, but nothing crazy. If that group is good and low by roughly what your calculator predicts with a high 2760 FPS MV, proceed.
Step four, measure that difference between centers of those groups, convert to MOA (example 10.1" x 100 ÷ (300 x 1.047) = 3.22 MOA difference at 300 yards), dial 3.25 MOA and shoot another 5 shot group. Report back with measurements.
This will 99% certainly sort this out.