I shoot 40 grain v max bullets in my 223,and 45grain speer spitzer in my 22 250 for coyotes, i used to ues 36 grain varmint gernades in my 250 but i had a few yotes run 50 yards or so and die, never had one to run off where i couldnt find it though, so i went to a biger bullet not much bigger though,i shoot light bullets because where i call there might be a bobcat come in and i dont want to blow a big hole in it, it would be worth less money that was so i shoot something that will blow up inside of them or make a small pass through,just shoot the bullet you want to shoot they all will knock a dog down if you put it in the boiler room,what i think is it dont matter how big the bullets is if you put it in the right place it will do the job,there are people useing 17hmrs and 22 mags to kill coyotes so if a 17 grain 17hmr bullet will do the job than a 40 grain .224 will do the job better.thats just my thoughts though. good luck in you bullet choice