You can have the most accurate rifle in the world, and if you feed it the wrong ammo it still won't group, every rifle is different and finding what works in your particular rifle is part of the owner's responsibility.
My very accurate Remington Mod 700 Varmint Special groups consistently under 1", and with the right load it shoots groups around 1/2", I was experimenting a while back and tried a load, it didn't group, it patterned like a shotgun! That was the first time I tried a load in that rifle that put 5 shots at 100 yards into about 12"! This wasn't an untried bullet in that rifle, but that particular combination of bullet and powder, that rifle really didn't like!