If you want to hand load buckshot shotgun shells, call
Ballistics Products, or e-mail them, with your questions.
These guys have all kinds of load data, shot cups, wads, shot,
buffer, overshot cards, etc. I load some #0 buck(I cast my
own pellets) with their data and components. With some
patterning, and good chokes, you can call a coyote into 60
yards, and it will be down...Provided the shooter puts the
pellets on the dog. 
I hand load for 10, 12, 20, and 28 gauges. The only time I
buy factory ammo is for fresh hulls, or waterfowl steel loads.
It isn't that difficult to match or surpass factory shot shell
performance with a little patterning, choke testing, and load
data choices. DON'T deviate from the load data. As stated
several times, shot shell loading is different than metallic
cartridge loading. In shotguns the first signs of over
pressure are usually a catastrophic failure in the shotgun.
As to the question of duplicating Hevi-Shots Dead Coyote load,
I don't see a supplier for the Hevi-Shot buckshot pellets, in
a quick look around the usual Hevi-Shot bulk shot sellers. I
wouldn't get hung up on that. Just use nickel plated
buckshot. With proper choking there should be little to no
difference in performance.
Squeeze
