Shotgun pellet energy at range

[max the dog]

Does anybody have an idea of how much energy a shotgun pellet will have at long range? The question came up while getting ready for a Coyote hunt on Illinois public land where it's a shotguns only situation. I'm using a sxs with a full/modified choke. I have hevi-shot loads from #2 to BB left over form duck and goose season and I've also got some lead 0, 00, and 000 buck.
I'm heading out to the range this weekend to pattern it to see just how far the shot can hold together. Depending upon the energy the pellets still have I figure on needing at least 5 to 9 in the vitals of heart, lung, and brain to make a clean kill. I just need to know at what range it's still going to have enough energy to do the job.

[HighDesertWolf]

go with the BB hevi shot you will have quite a dense patterned at 50 yards compared to the 00 buck but with just as much smack as #4 buck.

[Coastie]

Your ammunition manufacturer should have posted balistc information on all of the ammo that you have available. An individual pellet will have energy directly related to its mass and velocity at the point of impact (energy =mass X velocity squared) the more pellets you get into your target, the more enrgy is imparted to that object, so whichever of your available loads patterns best with your gun should be the one you select. Personally I would try the 000 Buck first as that should have the best result if your gun can keep the pattern tight enough. BB seems a bit light to me at ranges beyond about 30 yards, more than adequate for birds, but questionable for anything else, but that is just my opinion. Have you considerd using rifled slugs? If your gun canhandle them, and they are legal to use, they are good to about 100 yards with the new rounds they are making today. If I were going someplace with one thing in mind to do, I'd use whatever gave me the best chance of doing it right.