I can't say I have ever had any gun shoot 6" groups from coreloks, federal or whatever except my AR-15 with wolf. I do have a friend whose 270win shot 3-4MOA, and I had some left over shells with 4064 and 130gr gameking, and let him try them, and wow, it turned into a subMOA gun. But for some reason, thats the only load it likes. Its a featherwieght too.

thin barrels are finicky and reloading usually can find the right length/load, etc.