semi-problomatic, single, 5-shot record groups are either 99%+ luck with all the variables cancelling each other out, or, 99%+ everything being perfect in the benchrest game; all the others from that rifle-ammo-shooter system are larger. There's no way to tell which made them so tiny; luck or perfection.
Benchrest aggregates best represent accuracy of all involved; the more shots and groups in an aggregate, the better it is. Reality is, about a fourth to a third of all groups fired are larger than the average or aggregate numbers.
All groups for accuracy are not fired in competition after 8 AM the day of the match. Some are fired before 6 AM when the wind's calm and air crystal clear without subtle air currents to change bullet's flight path from shot to shot. And done by folks just testing their stuff in a remote canyon and not competing with nor against anyone dozens or hundreds of miles away from the nearest long range benchrest match.
I referred to a series of 10-shot groups at 600 yards in one such instance. That had 7 or 8 groups shot; I now forget how many exactly. They ranged from about .7 to 1.5 inches with an average of about 1.1 inch. Then a 40-shot group was made with the same ammo printing all just under 2 inches.
What's the size of the largest group shot in the six 10-shot group aggregate in NBRSA 600 yard matches that holds the record? 2.092", 2.7547" and 3.0479" is the averages and the numbers for the three types of aggregates which means the largest group in each was 3 to 5 inches.
In a fall, 1991, issue of Handloader Magazine's a picture of some .308 Win. Palma ammo with new cases, 3/10ths grain spread in charge weight and up to .004" bullet runout measuring 2.7 inches across the widest holes in a 20-shot, 600 yard group it was tested at; compare that to the NBRSA three 10-shot aggregates shot at 600 yards the biggest of which is 2.4824" so the biggest group's over 3 inches.
