nightcaller, having to shoot a couple of coyotes 3 times is not much of a test for shotgun loads on coyotes. No matter how good a shotgun load is, at times you will need to keep shooting them. Even with the best coyote loads there are many reasons for having to use more than one shot.
The heavier than lead loads pattern better than lead and penetrate much deeper than lead and they do work great on coyotes.
http://www.predatormastersforums.com/forums/ubbthreads.php?ubb=showflat&Number=777351#Post777351
Look on page 9 of GC sticky pattern thread at the top of the Firearms forum. Deeper penetration with more pellets hitting the target is what the heavier than lead loads will give you "IF" you hit the coyote with the center of the pattern.
The number 4 buckshot smashed up pellets I dug out of the catalogs were not as big around as a 00 buckshot pellet.I would never use 00 buckshot on coyotes because they don't have enough pellets in them. But a number 4 buckshot pellet that only goes half way through a coyote is not deadlier than a 00 buckshot pellet that goes all the way through a coyote.
The hard heavier than lead loads also break bones in a coyote much better than the lead loads do, if you have shot very many coyotes with these loads it is pretty obvious.
It doesn't matter if you are shooting lead or heavier than lead if you hit the coyotes with the edge of the pattern.
When people say they have shot a coyote at 40 yards or less with Dead Coyote or Rem HD BB or T shot and it just ran off. I think they have just barley hit the coyote with the edge of the pattern.
I believe too many coyote hunters are shooting too tight of chokes trying to extend the range of their shotguns.If the pattern is real tight at 50 to 60 yards that means it will be very difficult to center that pattern on a coyote at 35 yards and less because the pattern is so small.