That's the G7 BC, not G1. That's what comes up on JBM when you pick the Berger 250 VLD and it's credited as Litz estimated. The 0.390 comes up on the top of the results page. When I ran the 300SMK vs the 250 Berger VLD under the same conditions and starting velocity, the Berger got to 1000 yds with slightly more velocity. So the G1 BC is probably in the vicinity of 0.8??
Now this is all estimated and the bullet hasn't been produced yet. But for the mid case capacity 338s, this looks like the better bet over the Berger 300 VLD, the 300 SMK, or most 250 grain bullets now available. If you can get at least 2800 fps with the 250 Berger VLD, you will be near 1000 yds potential in my estimation. You'd be in the same ballpark as the Edge shooting the 300 SMK in terms of remaining velocity and wind drift.