while i have not killed as many coyotes as some, i have killed over 200. so i have more than a little data to work with.
in the very beginning i believed what i was told about fmj's, that they kill coyotes just fine and did not leave giant exit holes. we all know that fmj's do neither. the dogs run, and if any bone is hit there is a large hole on one side or the other.
then i used hornady 55gr spire points for a few years, mostly because i could get them for just over a nickel a piece. they did a decent job out of a 223, but i had some runners, and some large exit holes.
then i switched to winchester power points 55gr and ran those for a few years. again, i had decent results, but had runners about 1 out of every 5 to 7 dogs, and also had some large holes on the back side.
then i tried some sierra 60gr hollow points, first few dogs went down hard with no exit, but they were shot length wise looking at me. the broadside chest shots produced runners and large exit holes. the 60gr in a 223 just doesnt go fast enough for violent expansion.
then i tried some 55gr v-max, i had used them before in a 22-250 and had excellent results. i have been using them in the 223 for about 2 years now. i only have runners if the bullet hits them in the back end or just grazes them. i only have large holes in the same glancing shot scenario. EVERY coyote i have shot with the v-max out of the 223 that has been hit properly went down instantly. i killed 8 coyotes in the last month, 7 were dropped right there. the one that made it 50 yards was hit far back while quartering toward. the far back shot had a huge hole, the others had no exit and a 22 caliber entrance.
and the v-max costs about 15 cents a bullet, a whole lot less than some bullets out there, and the same as many bullets that do not work as well.