That is a theoretical G1 BC. A few years back SOCOM did some COTS testing for a new sniper system, the 408 Cheytac was one of the contenders. Even with a high muzzle velocity and high BC they were unable to hit the 2k target, with multiple shots. A standard 408 load should be supersonic past a mile with the published BC's for the projectiles.
Doppler radar tracked projectile flight, and the Cheytac became "wobbly and erratic" around 1400 meters as velocity dropped off, same as the 50 BMG from the McMillan Tac50 already in the inventory.
So don't think you'll be "good to go" with a high BC bore rider design, some of those bullets just do not handle the transonic range very well. The high desert air has a has a slower speed of sound, so you would think that those high BC bullets would fly better longer, but sometimes it just doesn't work out.
Machine guns are awesome until you have to carry one.