As those 10 shot groups open up, which they all do to some extent, how much error is attributed to shooter error, environmentals, mirage, etc?
none or all of it depending on how you look at it.
If I shoot 1-shot groups or 3-shot groups, and overlay all of my groups, the group-size ends up the same as if I shoot one big group. Of course if I get up and build a new position for every group that adds to it...but for instance if I shoot 30 1-shot targets like a rimfire benchrest target without getting up, and overlay all of those shots onto one target, the group doesnt end up measurably different than if I sit down and fire the same # of shots in one go at the same target.
I am just as likely to pull a shot shooting small groups as I am shooting large groups. So if you want to have a realistic representation of what the whole system--the gun/scope/connectors/shooter--is capable of, then it's irrelevant, because it's built in to each way of shooting groups equally. So unless it's a stupidly obvious called miss (would have to be on the order of an ND, shot the wrong target, etc for me to ignore it) I count them all--with a heavy gun it's pretty easy to manage this, but even so I can call misses reasonably well and I dont have the feeling that the shots making up the fringe of my larger groups were bad trigger presses or shooter error. So not much scientific to report here, more my gut feeling from playing around with this a bunch.
Mirage--I think this matters more, at least that's my impression. I notice it more in cool weather when there isnt any breeze. Generally a breeze helps with this. It's not usually an issue shooting a 10-round group, but if I shoot multiple 10-round groups fairly quickly I definitely notice it. That's actually my measure of when I let things cool, ie I can visibly see the mirage. Where i live we dont have mirage very often as a natural condition like many of you folks who live in more arid areas do, so it's pretty easy to say for certain when mirage is from the barrel versus what isnt. But under decent conditions with a little breeze the barrel can still be too hot to touch without seeing a measurable degradation of my groups.
Bottom line, I have let it cool, I have eliminated anything that felt like a pulled shot, and it doesnt seem to matter. So i no longer let it cool, I no longer ignore shots unless there is a 100% positive problem with shooter or gun. I do let cool, but only to deal with obvious mirage from barrel, which most of the time still allows for multiple 10-round groups before a rest. I usually pull out the 22 or a pistol and shoot that for a bit while rifle cools.
