Fred,
Actually, I was talking about 10-shot groups (or anything more than 3-shot) to provide a realistic idea of what a given rifle and load will do IF somebody needs or wants all the accuracy possible.
Here's an example. Most years I normally shoot quite a few prairie dogs, and while I always taking several rifles I use the .204 Ruger as my main PD cartridge. The .204 I used for a while was a Remington 700 VTR that would group 10 shots of its primary handload under 3/4" at 100 yards. This translates into a rifle that will keep all its shots in around 2" at 300 yards, or about an inch from point of aim. Now, I'm not talking about typical PD shooting conditions, but the inherent capability of the rifle and load.
Year before last I started missing dogs at around 300 after what I thought was a good hold. So I put it on paper again at 100, shooting another 10-shot group with the same load, which was closer to 1-1/2". Which meant the barrel was starting to go, so I replaced it.
But the same barrel would still average right around 1/2" for 3-shor groups, which many shooters would consider very accurate. But three shots simply don't show what ALL shots will do with a given rifle and load, and that's what I'm interested in with a PD rifle. Otherwise even a perfect hold at 300 results in too many misses, and that wastes far more ammo than using a 10-shot group as a basic test at 100, instead of cheaping out and only shooting 3-shot groups.
With many of my big game rifles, however, 3-shot groups are plenty. As an example that's what I normally shoot in my 9.3x62, and they average under an inch, good enough to sight-in, while a 10-shot group would be considerably larger, so is any animals I'm going to shoot with the rifle. I'm not going to use it on pronghorn at 500+ yards, and most of the time shoot animals bigger than deer at less than 300 yards. It doesn't really matter if the rifle shoots half-inch or 1-inch or even 1-1/2 inch groups, because any are plenty for trying to hit the basketball-sized vital zone of the rifle's usual game,m at usual ranges.
And this, of course, is why so many people on the other thread said they'd great results from shooting only 3-shot groups when working up loads and hunting big game. Most people shoot big game at ranges where 2" or even 3" accuracy at 100 yards won't make any difference at all, because the target's so big. Yet the same people will often spend plenty of time working up loads and shooting 3-shot groups they can brag about. If that's what makes people happy, then why not?
But 3-shot groups at 100 yards don't really have any relevance in actually hitting a SMALL target at 300 yards. At the same time they're no handicap in shooting basketball-sized targets at 300 yards, because there's so much room for error.
So yes, it depends on what kind of shooter you are, but also on the level of accuracy required for what kind of shooting you plan on doing.
