Re: .204 Ruger
I have had outstanding results in mine using 10x and just about any 40 grain bullet. Sierra lists the max load as 27.2 grains for it's 39 grain blitz king.
I feel that the reason people have trouble with 40 grain loads is the quality of the factory ammo. In cool weather i really goes wonky.
I prefer the 40 gr. nosler bt in mine as far as results on coyotes go.
For what it is worth, Eh!