In my opinion the likelihood of a clean kill with the CB round is not high. Head shot yes. Remember guys this is not even a standard velocity .22 long rifle round he is talking about here, it is a very low velocity low bullet weight CB round. It just happens to be in a long rifle length to facilitate feeding in many rifles. I am wondering if a havaheart trap might be your best bet here. As others have said you chances of getting caught are good. You are in an incorporated area, and the law is not really on your side. A 12 gauge turkey gun with full or extra full choke and a load of No. 4's or No 2's would be good to about 50 yards, and pretty safe. but a loud boom. A suppressed .300 whisper comes to mind. But I know you don't have one. I guess you could claim the coyote was trying to kill the dog if you have the stones to stick to your story, and it would even be true if they come back, they are likely to be looking for pets. We lost our outside kitty to coyotes a few years ago. He was big and tough, but not tough enough for coyotes. One of the most effective adjuncts to calling coyotes in is to use a stuffed toy dog as a decoy. But as you can see here, there will be someone that will turn you in for firing any gun in town, even if they know why you did it..
James K0UA