One factor folks may not be considering is altitude.
I reside at 4350ft altitude, and that does some significant things to Effective BC. Air density up here is only 85% of sea level. That can push the transsonic distance quite a bit further out, and reduce drop and drift noticeably.
The difference is in the Time of Flight.
Higher up, due to less air resistance, the bullet arrives sooner; having therefore less time to drop and drift, while retaining velocity better as the distances extend. For my purposes, it allows me to use a lighter/shorter bullet, and drive it a bit faster than the heavier one, while still keeping above 1300fps a bit further out. IMHO, I choose to consider the entry velocity into transsonic velocity zone as being 1300fps.
NRA rules I've competed under call LR 1000yd, and MR 600yd. My AR's for MR are factory Stag 24" guns; I have an identical pair of these for informal private competition, and am extremely pleased with their accuracy.
At my altitude, my 75gr HDY HPBT Match load may be worth a try at 1000yd. While BC is factory listed at .395; reliably verified data may put it at nearer to .350.
That's another altitude issue, since any BC value BC is only valid at a specified altitude, and Effective BC will vary with altitude as it changes, BC data without a corresponding altitude is incomplete data.
My load is Starline Brass, HDY 75gr, CCI BR-4, and 23.5gr of Varget, loaded to an arbitrary magazine length of 2.250". I consider this as a generic load for the 75, using is in 24" Bolt (1:9") and AR 1:8"), as well as 16" 1:7" AR.
Greg