Not officially group shooting, but here is a 600 yard target shot this morning, the circle is 8", so just over 1.3 moa, the white backer is 18", so 3 moa.
The goal has been to remove vertical with RWS R50 and a EC V2 tuner, most of the high hits were 2 other shooters I let fire the gun. The winds were roughly 6-8 mph from 2-3 o'clock. I am not getting high fliers, but around 1/10 rds hit short of target, not sure what to do but at least the misses are traceable.
True test will be a 6" target, but you can see by the hits on the 8", may not be impressive unless no wind.
The rifle, Rim X, 13tw Mullerworks barrel, Manners TCS, ZCO 527