we're talking "called" coyotes and when I speak of called coyotes I rarely ever take a shot over 250 yards, most are killed 150 yards or closer. Would a beginner with less experience be "better" off with a 22-250, yeah maybe. BUT, that same beginner with the under standing of the importance of shot placement would also do just fine with a .20 cal., as long as he understands he's not armed for long range kill shots.
I had 12 different guys that joined me to call coyotes this past winter. They killed close to another 40 coyotes with me. What I noticed is most aim for center mass. My theory is, aim small, miss small and favor the front 1/3 of the coyotes body.
There's no doubt, as you drop in caliber the bullet placement becomes more critical. And a bad shot with a sub-caliber will result in a lost coyote quicker than a bad shot with a .24 cal. or larger simply for the reason of "lack of blood trail".
Not many guys can consistantly pull off shots in the field off of shooting sticks out at 500 yards and further. Heck, I don't even shoot at 'em if they hang up that far out for a couple of reasons. I lack kinetic energy and I suck at long range shooting.