A word or two on stopping power. I've been a Firearms instructor for a Federal Law Enforcement Agency for the past 14 years. The term "stopping power" is probably the most abused phrase in the gun owner/nut vocabulary. Handguns to put it in simple terms are nothing more than varying sized hole punchers; a .45 punches a bigger hole than a .22. Of course you can mix in hollow points of varying descriptions (gold dot, hydro shok, black talon, et al) that do little tricks to make the hole a "little" bigger by expansion, etc.
Unfortunately the terms temporary wound cavity and permanent wound cavity come into play here and unfortunately this is where handguns come up on the short end of the stick.
Handguns or pistols, suffer from low velocity rounds (when compared to long guns) so their wound cavities amount to punching a hole with a jagged stick. Of course if the round exits the other side, it can produce some nasty looking messes depending where your shot is placed (discussed later). Long guns on the other hand produce massive amounts of damage and horrible permanent wound cavities due to their velocities.
An example I like to use when teaching a firearms class is consider taking a small stone and holding it above a puddle of water say 3 feet high. If you let the stone drop, it will create a cavity/tunnel temporarily through the water. The ripples will go out from the point of impact and you may even lose some water from the puddle due to splashing but the majority of the water will return when the ripples reach the edge of the puddle and come back <--thats a pistol round.
Now take that same small stone and rare back like a baseball pitcher and slam it into the puddle releasing it from three feet away. You immediately loose all kinds of water from splashing and the ripples will be so violent that many will escape the borders of the puddle and never return. <---Thats a rifle round.
Remember, the stone is the same size; it’s the velocity that matters. In a pistol that you want to carry for "stopping power" of a coyote or any other animal for that matter, you are “dropping the stone into the pool”. What counts is shot placement, vital organs, brain, central nervous system, etc.
A couple of cases in point; my very good friend at a small east Texas police dept. was called to a domestic several years ago, things went very bad when the (very average sized and sober) husband grabbed a .357 from a drawer. My friend was carrying a .9mm at the time. He quickly drew his weapon and shot the man 4 times in the abdomen. Thinking this would stop him, he paused, and the man winced from the pain but turned and fired once at him. Seeing the weapon pointed at him, my friend stepped back tripping over a chair and fell to the floor. He believes the man though he had hit him because he fell. The husband then turned to my friends’ partner and shot him twice in the chest. My friend’s partner fell to the floor. Seeing this, my friend came to his knees and emptied 10 rounds into the man. The man staggered but had enough left to put one more round into my friends partner, killing him. My friend fired one last round into the man’s ear ending the situation. My friend no longer carries a 9mm.
Not too long after this, a man was causing a disturbance at a local bar at a nearby town when one of their officers responded, a very large, intoxicated man charged him with a knife. This officer also carrying a 9mm, placed one round, center mass dropping the man instantly, game over. Shot Placement!
Knock down power often used interchangeably with stopping power is a largely myth. Simple laws of physics, "For every action, there is an equal and opposite reaction" So the stories of shooting a man with a .45 and having him fly backwards through walls, windows, doing back flips is BS. If it had the power to do that, it would also knock the shooter down as well. You’re punching a glorified hole, nada mas. Now there are other issues that come into play such as does the round have enough penetration to hit a vital organ, fragmentation, etc.
My advice, if you want to carry a pistol for defensive purposes, for coyotes, bad guys or whatever. Do like someone said above 1.) get a gun that’s comfortable to carry – a big massive desert eagle .50 cal will do you no good if its too big to carry and sitting in your drawer at home when the caca hits the fan. 2.) Spend the money and get a reliable weapon. Caliber is up to you and what you’re comfortable with. When I’m out fishing or hiking, I carry a colt mustang .380 but have been known to carry a .22 when I really want to go light. If I’m in a bad area or on a long trip, I carry my H&K P2000 .40 cal. Dress for the occasion I guess. 3.) and MOST importantly, learn to shoot the weapon! SHOT PLACEMENT, SHOT PLACEMENT, SHOT PLACEMENT. Remember--> sight alignment and trigger control. If you should come across that one in a thousand coyote that is 115 pounds, foaming at the mouth Rabid, has fangs 8 inches in length and has an uncontrollable desire for human flesh, shooting him in the ass will only give you something to laugh at as you pass through his behind two days after he has consumed you and needs to poop.
Enough rambling..just my .02 besides, talking guns, knockdown power, caliber size, best round, etc. is ALWAYS a recipe for arguments.