Shot to shot drag variability was being discussed by serious LR shooters many years ago. I think Bryan Litz even mentions it in the 2nd edition of Applied Ballistics for Long-Range Shooting (Copyright 2011).
The reason very few paid attention was (my opinion) the difficulty in measuring it. Basically had to have Radar or a way to measure MV and time of flight or MV and downrange velocity (not as easy as it sounds).
Now we have consumer-level radar units that will record downrange velocity (if you shoot close enough to them). We also have the Oehler System '89 to measure time of flight.
The System '89 didn't really take off in popularity as much as was expected. My opinion is that most people don't want to fool with skyscreens and long spacings.
All that has changed (or is about to). The software for the '89 has been modified. It will now allow you to put a microphone near the muzzle, put instruments downrange, fire a shot, manually input a MV and, using atmospherics and TOF, will calculate BC on every shot.
Therefore, you can see the BC variability. You can also use it to calibrate a radar measured drag function.
The hassles of skyscreens are no more! This system may not be as easy as shooting over someone's big radar system but it is the next best thing.
Has Hornady figured out a way to reduce shot to shot drag variability? I don't know. What I do know is that tools currently exist for the enthusiast to find out.
Two radar chronographs = $1,200 or the System '89 is about $3,000.
The two chronograph system requires you to hand-jam the info for each shot, gather and summarize the data. It also requires you to be able to see the downrange chronograph display so that you are certain you have the correct data match (downrange cameras, iPhone on Facetime, etc). The downrange eqpt. also needs some sort of protection or is in jeapordy. Distance becomes a problem though I know of it having been done at 800 meters. They got some good data and only shot one unit (they have a big budget so, no worries).
The System '89 spits out data within seconds of the shot, produces a report at the end of testing, has a broad target area and has been used successfully at 2 miles.
Looks like technology advancements are going to continue to make the future exciting.
On a personal note, I've been using skyscreen chronographs for 45 years or more. The first one I used had paper screens - had to be replaced every shot. I thought the light screens were a great advancement. With the normal lifespan of electronic stuff, I think light screens had "a pretty good run".
I won't miss them, though.
