I have found a way to keep coons from destroying my feeders. It's a large bug zapper like device. I made a normal type varmint guard from hardware cloth. The type you would use to build a rabbit hutch. Inside that guard I place a smaller guard which is epoxied into the lip of a lid from a five gallon plastic bucket. I cut a hole in the center of the bucket lid to go around the feeder motor. The plastic lid is attached to the bottom of the feeder and serves to insulate the inner guard from the feeder.
I attached a capacitor from a disposable camera to both the inner and outer varmint guards. When a coon tries to reach through the guards, he closes the circuit and gets the piss shocked out of him.
The "varmint zapper" is recharged from a 6 volt battery with a solar battery charger.
The best feature of my home made zapper is that deer can't get shocked. The only things that can receive a zap are critters that can poke a paw through the one by two inch outer mesh wire and touch the inner mesh.
It works so well that the coons have learned to leave the barrel feeders alone.
My on demand feeder required a different approach. The only draw back here is I have to replace the carpet tacks occasionally.