Get a better trigger, even if you don't get better groups you will be happy with the upgrade. The Larue MBT is an excellent value. https://www.larue.com/category/parts-acc.../triggers/
There is a lot of jiggle going on in an AR platform compared to a bolt gun, upper to lower, bolt and carrier moving back and forth, flex in the whole system. For me it takes nearly double the effort to shoot well with a Grendel than a bolt gun. The amount of stock to shoulder pressure, downward pressure from the pistol grip, cheek weld pressure, a round forearm and trying to keep them consistent is hard.
There is a lot of jiggle going on in an AR platform compared to a bolt gun, upper to lower, bolt and carrier moving back and forth, flex in the whole system. For me it takes nearly double the effort to shoot well with a Grendel than a bolt gun. The amount of stock to shoulder pressure, downward pressure from the pistol grip, cheek weld pressure, a round forearm and trying to keep them consistent is hard.