I think the best thing you can do is run a ballistics program for your load and find out what the foot pounds of energy is going to be at different ranges.
I was told that a good rule of thumb to go by for Foot pounds of energy for killing Coyote would be for that every pound the animal weighs, 10ft/lbs is recommended for a good kill. So, a 25lb yote would need 250ft/lbs of energy.
With the information that I have gotten from a ballistics table, my load will deliver 271ft/lbs of energy at 400yds. IMO, that is enough to kill the average yote in my area but I have discovered that my abilities limit out to around 300yds tops.
While I said that 300yds is pushing the capability of a 223, I did not say that it is beyond the capability. It's just beyond my capability past 300 to make consistent lethal shots. Sorry if I gave the wrong impression there. :oops: