That rifle and caliber will shoot very far. For a few years, I used a 20 inch AR H-Bar with a 9 twist and 69 Sierra's on the 600 yard Nat'l Match slow prone line, and then went to the Hornady 75gr OTM for better wind resistance. That rifle with 1/9 twist did not stabilize the 75 AMAX well, so I stayed with the shorter OTM. In my 24 and 26 inch 1/9 twist, I used the same 75 OTM, Amax, ELD's and Bergers on the 1,000yd line and some beyond. In my 1/8 twist and using the 80's, its a very different world.
I have used the 55 and 60gr NBT in a 1/9 twist on P-dogs out past 800.
Late Entry: Also, I have 2 M-4 models with 16 inch barrels and 1/9 twists, and I use the 68/69gr bullets on the 500 and 600 yard gongs. Those rifles wear scopes of 2-7x and 1.5-5x CQB Mil Dots, and it is fairly easy to engage the longer ranges.