It is not the 4th shot every time. Any one shot could be the flyer. Direction of the flyer seems to, primarily, vary between 9 and 3 o'clock.

My test procedure it to shoot 1 fouling shot from a clean barrel.
I then shoot a 4 shot group. I chose four for load development in case I noticeably pull a round -- it gives an extra shot to see if that particular loading has potential and warrants another test.

I let the barrel cool, between strings, until it is luke warm to the touch.

This is the only 30-06 I load for, I set the dies per RCBS instructions. Should I be doing something different?
In the past I full length resized my brass -- but I now only neck size.

I have not chronographed my loads yet. I just purchased a chrony.
I do not own a concentricity gauge. Maybe I should.

Brass: Winchester or previously fired Hornady (says Frontier on the case)
Powers: Varget, IMR4831, H414
Primer: CCI large rifle BR
Trigger is the new adjustable Remington trigger. Set at about 3.5 pounds

Looking at the bolt now. No, It does not have even wear on all sides of the locking lugs. As a matter of fact -- they are not even close to having the same wear pattern. Maybe that is it? Any idea on what I am in for ($$$) to have it trued up/ blueprinted?

Thanks.