I've had more "404" errors trying to find references to group testing at different ranges than any time since I tried to find the "concept of design" for reloading article...
On page 2 or three of this thread "alinwa" explains his testing at different ranges.
Bryan Litz used acoustic screens to test bullet flight every 200 yards, but his old personal site is offline now. I'm not going to pester him for the data.
The common theme with these test setups with acoustic screens is that no one tracks the initial instability of the bullets in the first 50 to 80 yards.