I have a Remington 7400 in 280 Rem, the best accuracy I got with IMR 3031 is 44.5 grains with a 150 grn core lokt (7/8", 4 shots, 100 yards).
I believe the starting load was 43 grns and max was 46 grns. The best load with Nosler BT's was 45 grns (1", 4 shots, 100 yds).
I have never tried Barnes bullets, but I have been interested in the Nosler E-Tips,
Nosler provides info stating; not to load to max pressures due to the construction of the bullet, that E-tips reach max pressures sooner than conventional bullets.
I assume that Barnes are the same way !