Re: .40 S&W or .45 ACP for song dogs???
Living in Canada, I've never owned a handgun, and you can't legally hunt with or carry handguns here so I have no experience with that either.
Nonetheless, I see it weird how there is even a debate that the .40 S&W or .45 ACP COULD kill a 25-40 lb coyote, when they are both considered excellent guns for personal defense against two-legged varmints weighing 150-250 lbs.
Shot placement, folks, it's been said here before. I've CLEANLY killed a pile of coyotes with the .22 WMR and, more recently one with my .17 HMR.
Precision > power