In a distant lifetime when I was very anal with my comp loads, using mandrels in .0005" increments and turning necks to within .0005" of each other trying to get ever increasing minimal runout. I twigged that perhaps I was wasting my time.
I ran a test with everything the same except the amount of runout. 11 rounds of each fired in the exact same conditions, same day and barrel cleaned of carbon before each string, which I shot just as I would during a match. They went .001" runout, .003", .005" & .008". 10 rounds fired with the 11th round chambered and removed & carefully stored as to not induce any bullet movement. Which they were later retested and found that except for the .001" runout cartridge, all the others had changed by at least .002" and the .008" set had gone back to .003" just form chambering them. All loads were just kissing the rifling, not jammed by any means.
I could NOT decipher any discernible difference between the 4 groups, normal deviation of velocity could have influenced any one of those groups to look how they did. All groups were within my normal outcomes @ 600mtr and what I expect from that barrel. There wasn't a single flier amongst the 4 groups and they measured within 1/16MoA of each other.
I repeated the same test in my 6.5x47, it had the same results, it just didn't influence the end result in any measurable way.
I have seen greater shift in groups from vertical influenced by velocity swings than I could see from these 2 tests.
All loads used were highly tuned which I feel is more important than a bit of eccentricity in bullet alignment.
With partial sizing, the case is free to self align with the bore and chamber, which I feel compensates for slight eccentric problems.
My 222 has a fair amount of runout, it still shoots tiny little groups with tuned loads.
Go figure.
Cheers.
