Depends on how much of the coyote (and its pelt) you want left. With a caliber as large as .30cal, your best bet for a pelt saving load is probably either a FMJ or an expanding bullet designed for penetration more than expansion. Just be cautious with the FMJ's, because they can and will ricochet very easily. Be even more cautious of your backstop.

If you just want to make the coyotes dead, a light varmint bullet is just the ticket. Speer makes the TNT in .30cal, and Hornady makes the V-Max in .30cal as well. Another advantage of a varmint bullet is there is little chance of a ricochet. These bullets are very fragile and will disintegrate instantly on impact with any semi-dense object.

Mike