The most accurate loads with 168's from a .308 case I know of have all used IMR4064 powder. Same for 175's up through 190's. Some test groups at 600 through 800 yards are smaller than current benchrest records.
But you have to weigh charges; metering IMR4064 is a bit tricky.
168 gr. Hybrid
43 gr. Varget
Lapua Palma brass
Fed small rifle match
2.880 OAL -.060 off the lands
2750 fps
26 in Krieger 1 in 10 twist
1 1/4 groups at 500 yrds.
Tarey
Rifle and Bipod built by ME
If I do my part it will shoot 5 shot 1 1/4 inch groups at 500 yds. I have shot a couple smaller ones and bigger ones but that is about average, and that is prone off the bipod. I guess I got lucky and got a good barrel.
Tarey
45 grains of varget in lapua brass is what worked best in my Rem 700 sps with a 26 inch barrel. My next best choice for that combo was 4064. Didnt see much difference in accuracy with the 168s but the 175 smks prefered the varget. I also noticed a slightly smoother recoil impulse with varget and the 175s.