http://www.mssblog.com/2019/08/09/reloaders-corner-standard-deviation-2/
Just a FYI, I didn't write it, you may or may not find it useful.
Let the debates begin.
I read it and agree mostly with what Zediker is saying. My general rule is that extreme spreads are more important than standard deviations. His long range argument is of course, nice mathematically. Wide extreme spreads will string the shots up and down the further you go out. But this is getting to be Long Range mental/physical stimulation stuff. Glen does give 10 fps as a good value for extreme spread. A long range champ I know said he wanted loads that had SD's10 or less and ES's 20 fps or less. I have examined almost all of my rifle data, and have seen this maybe two times, and it might have been a statistical fluke. Another bud of mine, a F Class champ, was bragging about a cartridge of his that had 2 to 3 fps extreme spreads (?). Maybe he meant SD's, I don't remember, either number is beyond belief. I do believe for the long range crowd they really want low velocity extremes, which then, would give tight SD's.
But I am also going to say, there is a lot of mental/physical stimulation to this, and no one I know shoots in a vacuum. Wind will blow your bullet yards out and if you are not a good wind doper, the tightest SD's and ES velocity spreads wont make a difference if you can't keep the shots in the ten ring. I recall complaining about the 600 yard winds the day before, as I was pulling a target on Vaile. A Ret USMC shooter stumped up (we were in a relay change) and told me that when he won the 1000 yard match, he had full left windage on his M14 and was still aiming at the third target to the left. Based on the clicks on my 308 NM Garand rear sight, I have from center to total right, 34 total clicks till sight base stopped. Since these are half MOA, the MOA is 17 MOA. At 1000 yards, that would be 10 inches X 17 =170 inches, which is 14 feet of offset due to rear sight adjustment. Then, if the shooter is aiming three targets over at 1000 yards, assume 12 foot target centers, 36 feet plus 14 feet equals 50 feet of wind drift at 1000 yards.
Now, a few inches of bullet drop at 1000 yards, due to velocity variations, is inconsequential compared to 50 feet of windage drift. Get my drift?
Zediker has always had the unfortunate habit of selling gimmicks as if you can buy better scores with better equipment and cut out the parts about shooting skills and practice. I can say, by the time you do observe the phenomena of bullet drop out at distance, due to velocity variances alone, you are one damn good shooter.
