I am a 17 HMR advocate and I get so sick and tired of all the speculative bunk that is said whenever this issue comes up. Everyone and thier dog "shot one perfect and it got away" and if that isn't the case they have never even tried it. They simply speculate. Well how about this.....
Who here would shoot a 225 pound whitetail at 200 yards with a .243 and 100 grain bullet?? Probably everyone, that would be considered a slam dunk, not even close to marginal.
Well that setup at that range (based on ballistics from the Hornady ammo website) would be producing 1397 ft lbs. of energy. On a 225 pound deer that is 6.2 pounds of energy for every pound of animal.
Now, who would shoot a 25 pound coyote with a 17 HMR and 20 grain XTP at 100 yards? Most wouldn't. Well guess what? A 17 HMR at 100 yards generates 140 ft lbs. of energy. On a 25 pound coyote that is 5.6 pounds of energy. Very close to the same ratio you would be using on that deer above with your .243. Hmmmmmmmmmmm?
I've killed a bunch of coyotes with a 17 HMR. Is it the perfect/best coyote gun? Nope. Will it work. You bet, just keep the shots close and in the vitals. And don't tell me you hit the vitals until you have recovered the animal and done a bit of an autopsy to see what really happened because when shooting at game a lot of what occurs happens faster than the eye can see. I've recovered a number of "perfectly hit" animals that were actually gut shot or worse.