Sambo hit the nail on the head (IMR 7828 & 160 NABs)
In my rifle, a dose of 87g of IMR 7828 loaded at OAL 3.68" does the best with the 160 NABs. 87g of 7828 get me 3350 FPS and one hole at 100, 3/4" at 300, and 3" at 500 yds (with 2100 Foot pounds of Energy at 5).
Keep in mind that this is a carry rifle... not a heavy rifle: it has a S/S, #5 contoured, 27" fluted Shilen barrel, action is all trued up, a jewell, a McMillan Classic stock, a Zeiss Conquest at 4.5x14.
All total it only weighs in at 8.5 lbs.
With 140g NABs, and 91 g IMR 7828 it gets me comfortably 3600 FPS with very similar accuracy and has 2045 Foot Pounds at 5.
The difference between the 140 & 160 at 800 yds: the 140 g NAB retains about 1300 FP... whereas the 160 NABs retains 1400 FP.
I guess it is according to what you want to kill.
v/r