Having experience with the 308, Grendel and 224 valkyrie I developed a preference for the Valkyrie for accuracy at distances where the grendel failed to live up to it’s hype. The 6.8SPC case gets more performance out of same powder charge it seemed to me, but then I’m no expert.
I built a psa 300 blk pistol with 7.5 barrel and it is very accurate out to 100. 150 yds. Best load for me has been 110 gr vmax on top of 19.5 grains of H 110
I too use unique after trying others. It takes so little and easy to keep off the shoulder. For inside neck I just scrape a tiny bit of residue off a finger about every fourth case and no problems after 3 years.
I got good results with hornady 123 gr set using 27.3 grains of h4895. 200 yds grouping was very good. As for factory, Fed premium gold medal Berger 130 gr put 3 rounds through touching holes at 200 yds. Doug in New Prospect SC