The favourite load in my one 280AI was the 150TSX at 3050 fps, with around 62.5 grains H4831 Extreme (slow lot). It had a 9 twist 24" barrel.
Other loads were the 140 at 3160 with the same powder, and the 120 at about 3375 with H4350.
With the 140s I got 3200 fps with RL22, but 4831 was more accurate.
Same with 7828 and the 150s, more velocity but the 4831 loads were so accurate I stayed there.
