Ned Ludd
Silver $$ Contributor
More is always better. That said, groups don’t get smaller by adding more shots. A smaller number per group will get you in a rough tune quickly. But if you want to discern a good load from a great one with any confidence, you’re going to have to shoot more than a five shot group to verify. You can take advantage of the fact that groups are not truly independent to help guide you and reduce round count. If you’ve got a huge group right next to a small one, there’s a good chance one of them is lying to you, for example.
Those lying little holes in the paper!!! LOL. The question is which one is lying? I believe it is rare, or even nonexistent to have a group shrink up tight to one ragged hole by the influence of outside random factors (i.e. wind, shooter error, etc.). So I generally would believe the huge group right next to the small one would be the liar. Nonetheless, that's where a 5-shot group can sometimes help with your confidence level. If you put 4 into one ragged hole, but slightly jerked one shot, or maybe you saw your wind flag jump out right as you let one shot go, that's usually a good sign the load has promise, even though the group spread might be wrecked with that one hole that is out.
For the OP - the whole point of the OCW test approach is to find two (or more) successive charge weights where the center points of each group impact the exact same relative spot on the target (i.e. not moving around relative to point of aim). It is not about the smallest group. The idea is that you will have then found a charge weight "window" across which velocity/barrel harmonics tends to put bullets into the same point of impact. These OCW windows are analogous to having several successive increasing charge weights print holes at the same vertical point in a ladder test. Again, you're looking for a charge weight region where barrel harmonics produce the same vertical POI. The important point with the OCW test is that three shots is sufficient to locate the center point of a group. Chances are that adding two more shots to each group won't change the center point of each group by very much.