Here is the scoop boys. Though it's not a 204, I use a 20-250, a true 400 yard gun. The only bullet I have found that will not splash and reliably/consistently kills coyotes is the Nosler 40 grain ballistic tip. I've killed 1000+ coyotes with this gun. In my case, velocity is at 4300 fps , and any lesser bullet simply splashes at that velocity. The solid base of the NBT makes the difference, always penetrates and exits.
31 grain 20 caliber Hammer Hunter Bullets arrived yesterday and I am anxious to try them in the 20-250 for non lead California coyotes. I reckon somewhere 4400-4500 fps, we shall see, load development starts today. I hope they "shoot" and kill adequately, that would solve my non lead bullet dilemma for CA.
BTW, I've killed a lot of coyotes with a frontal shot(coyote facing me). Every time, the animal went straight down, DRT, never took a step. However, that is a smaller kill zone. Drift left or right due to wind or wobble and a shoulder hit occurs, resulting in a wounded animal.
One last thing, i started out with a 1:12 twist and found it wasn't enough twist for a 40 grain bullet and replaced it with a 1:11. I've seen the same scenario with friends 204's where their factory barrels would not stabilize 39 and 40's either and were forced to shoot 32's.
Cheers! Gary