I have a White Oak Armament 6.8 upper with a Shilen Match SS 18" barrel 1-11" twist, 4 groove. Close to $700 with a PRI magazine.
I get .750 groups with the Hornady 110gr BTHP and 29.0grs H322 and CCI 400 primers in SSA brass 2658fps at OAL 2.295"
Mt best targets are with the Hornady 120gr SST and 26.6grs H322, OAL 2.295" at 2399fps; .341 I can push them to 2533fps with 28.1grs H322 and CCI #41 primers but they spread out to almost an inch.
Working with a Berger 140gr (B.C. 487)and AA2200 and H322.