First things first, you need to check everything when there fliers in question.
Check bedding by sooting or Prussian blueing the action and fitting it with the correct torque on the screws then fire it 5 times. Disassemble and check for rubbing/ movement ANYWHERE in the bedding.
If it doesn't have pillars, get it pillar bedded.
If it has an aluminium bedding block, skim bed it and the recoil lug, only clearance that is necessary is underneath the lug.
The only other reason a barrel can produce fliers is if the barrel walks shots as it warms up, this is often due to insufficient stress relieving.
Seating depth can also walk bullets all over the target, these are not fliers per se', but the harmonics walking the POI.
Try seating depth in .010" increments with 3 shot groups AWAY from the touch point.
Once the tune is found, fine tune with .003"-.005" above and below that point.
You use a powder that is just above a mid range burn with a middle load, say 3g below max and test.
You may be surprised that a primer change can also affect a load in a huge way for the better.
Cheers.