Re: Chronograph question.
Brent, excellent observation, however, we have seen "round" groups with different vel readings. What I mean is that a "slow" vel shoots higher then a "fast" one, or to the left or right. We have forgotten that vel also relates to barrel time and its harmonics, which in turn determines what barrel location the bullet sees as it leaves the muzzle.
There are so many variables in shooting that vel alone cannot determine accuracy. However, if I had two equally shooting loads, I would choose the one with the lower vel variations..just in case.
Ultimately, the only way to know how a load performs is to shoot is at the range you want to use it at. Like Brent, I have personally had several one hole loads at 100yds that wouldn't stay on a piece of paper at 500yds.
Now, I work up my loads at 180 or 250yds. I find this to be a better representative of LR performance. In general, if a load works well at these ranges, it will work well at further ranges. I find wind and conditions to play a bigger roll at that point.