I use Buck for coyotes. Use a super full choke actually called a predator choke in a 870 express mag. I patterned all Buck shells from #4 to OOO at 40 yrds. and got the best reults from #4 and OOO buck. The rest were hit and miss with a good chance of non-lethal wounds. Sometimes the OOO Buck will destroy pelts, depending on the range.
I also found out that the OO Buck shell is primarily used for close range self-defense, as it opens up quickly past ten yrds.