While this is not particularly practical it may be that research into how to make such shots have application in extending the range in more ordinary situations:
They started at 100 m to establish zero
Then to 1000 m to confirm zero. Then to 3000 m. They ran into problems with ranging binoculars (Steiner & Vextronix) “stalling out.”
Consistent muzzle velocity is key. Their loads were within a small range, but a 1 m/sec change in muzzle velocity causes an 80 cm vertical shift in impact point — meaning 1 fps change alters that impact point almost 10″ in the same direction. So you see that firing at 4000 meters is really at the ragged edge of what’s possible with field-employable sniper-type equipment, in 2016. At 4000 m
Third, or possibly, fourth, shot was heard to connect by a forward observer.
Also, dropping a projectile in on a group of bad guys from such distances may cause them to slow or stop their current activities and attempt to deal with the perceived threat with low cost and little risk to the shooter. Sometimes slowing down enemy activities or distracting them, even by a small amount, can result in significant changes in outcomes.
Via email from kb.