Over the past four years my partner and I have been fortunate enough to take over 150 coons. In the course of our travels we experimented with a variety of calibers and cartridges trying to find the perfect coon gun. What follows is an account of what we found to work and why.
Lets set the stage for just a second. Most of our coon are on the move between 15-30yds when taken and pairs are the norm. We also tried and tried but at the end of the day we decided we wanted a cartridge that would put them down quick with a center mass body shot.
.22 rimfire= Too often its not enough. You will cripple coon!
.22 magnum = Can't give a solid nod this direction either. My buddy had one for a short time but it was paired with a red dot, not a precision set up. May be right on with a good 3x9 scope.
.223 = Great if you hate skinning them! We've had excellent success with reduced loads using shotgun powder and 40gr V-max's. Little entrance, no exit! They crumble everytime, no matter where they are hit.
20 gauge = rarely enough!
12 gauge, 2 3/4", #4 buck, mod. choke = works every time! 27 pellets, minimum pelt damage.
.22 Hornet = untested, but the velocity and energy would be right inline with our reduced .223 loads.
In Kansas, a 12 gauge autoloader is the way to go! Hands down. Especially when a coyote runs up on your coon set, we are always in brush and trying to find a running coyote in your scope in a stand of trees is tough at best.
Hope this helps and good hunting!