Has anybody used 5.56 FMJ bullets on coyotes? I've got a few K of milsurp ammo but I won't use it if the bullets just punch a hole in and out and the animal runs off to die. 
A close range .22 can punch a hole in and out of a Coyote and it will run off on you for sure.
Your centerfire is hardly a rimfire (velocity wise) and will generate perhaps 1200 more ft lbs of energy.
What this means is that when even a "tough" bullet enters living flesh at high velocity, there is going to be a massive amount of hydrostatic shock released that is initially going to open the wound channel to great proportions.
The Coyote (even some of our 60 lb eastern types) are simply too small of a critter to take this kind of abuse and a hit near the boiler room is often going to mean instant lights out as the cnc has recieved a sever shock.
When you skin that Coyote out, It is common to find large areas of bruised, bloodshot meat around the wound channel which verifies that the hydrostatic shock does happen. This is something that you knew already.
Please note that velocity needs to be present for this to happen.
If you operate strictly within Calling Range like I do, the fit is going to be like hand in glove.
What is calling range?...I am going to say 150 yds max but usually closer. I do not like them to get much under 100 yds because even that "tough bullet" out of a centerfire can create a rip in the nearside hide.
What is a tough bullet?...For me it is the 55 gr Hornady #2267. It is a .224 FMJ-BT. I shoot them out of a .22-250 for an actual velocity of around 3,591 which is 169 fps under the 3,760 claimed in my load data.
Ricochets?...Your darn right a bullet will ricochet and my .22 lr is the worst offender as the bullets will bounce all over the place (if you let them)..Perhaps we could compare this to a fmj .223 at the 400yd mark? even if the bullet happened to be a softpoint, would there be enough velocity left over to make the bullet mushroom out instead of skip or bounce?...Do we really have any buisness shooting a 150 gr or heavier bullet out of the likes of a .25 cal bore or larger? The answer is yes because we are sure of our backstop, the number one rule.
We are talking about a varmint class bullet "55gr or under" touching down at 150 yds or under (read calling ranges) while still moving at or over 3000 fps. Such a bullet in this weight class is can be notorious for leaving the jacket behind whether in the form of large amounts of copper petals which can be found at the surface of the dirt berm or even the entire jacket which can be left behind in a lot of different media while the lead core continues on through.
The jackets on these lightweights will survive the likes of passing through a Coyote though with the benifit of getting a small in and a small out which is important if you skin everything out like I do.
Richard, I do not have any idea how tough that your milsurp fmj ammo is but again, is going to be a lot more fragile than the likes of a 170gr out of the bore of your 94'....I would use that ammo but keep your backstop in mind or calling ranges where that bullet is going to touch down quickly.
This subject does come up over and over again as claimed and I find myself the "odd man out" on the majority of these post's and I usually avoid them because it can take a month for the hair to grow back on my arms n eyebrows after the flaming is done. I have avoided them at least until today!
Some of my Best or Worst arguments here were with the late Lawdog. Lawdog thought that I was crazy on the "velocity kills" issue and I, in turn, wondered if he had ever shot a Coyote in his life. Lawdog liked to use the .22 Hornet and an expanding bullet that did it's job well out to 150 yds with the bullet often staying in the yote. Reflecting back on this, I think that it would be an excellent combo for the caller but don't own one yet so I continue to use what I have and am getting hides that are worth skinning.
