Just a thought here. A 25 shot "group" isn't. It is probably best called a sheath of trajectories and demonstrates what a particular rifle/ammunition/shooter is capable of. We can all field a few minuscule 3 or 5 shot groups which we proudly display on the wall or post online. The more accurate measure of the ingredient combination, is the totality of all those 3 or 5 shot groups put together.
When I shot in the service, each range session target data was measured, evaluated, and recorded so as to demonstrate performance over time. It showed marksmanship performance mostly and the Gunny would know if I learned anything. It demonstrably showed performance degradation if a 3-month hiatus occurred. It then showed a return to peak performance after a few weeks back on the range getting trigger time.
It also showed a gradual decrease in performance due to equipment degradation like bore or throat erosion. The bottom line was constant data logging and monitoring over time.
I believe what I am saying is that group size probably isn't the performance indicator we think it is on a particular day. It is a snapshot of particular ingredients that hour or day only. I would surmise that a 25 shot group is a b**ch to keep tight due to a variety of things, namely shooter fatigue, eye strain, stress, shifts in the shooting platform, rifle/shooter mounting variations, temperature shifts, wind variations, and other variables attributed to performance of the package.
So I suggest a 3-shot group is a lie we love to believe, and a 25-shot group involves too many variables BUT is more telling of the "package" performance due to its involvement of most variables affecting performance.
I truly love my 3-shot groups (the ones I keep) and dread a days worth of data combined. Either way, I enjoy my shooting now that the Gunny is not stomping on my head and calling me all kinds of unflattering names.
Oh yea. I forgot to mention what the data yielded for each shooter/rifle mix. The USMC knew without a doubt what my precision hit percentage was at any given range. So at 250 meters, I could surgically hit with 98% probability. I could zone hit with 100% probability. At 800 meters, I could surgically hit with 88% probability and zone hit with 94% probability. So in any given theater on any given target, commanders could assess the result of a shot from me being effective. Camp Perry values surgical precision. Combat theater values zone precision.
Probably TMI but what the heck. Now that I have kicked the hornet nest, the following should be entertaining to read. Get to typing guys!
With rifle in hand, I confidently go forth into the darkness.