What caliber for Sage Hopper?

I was actually thinking of necking down a 12 ga to 20 ga.
 
My wife showed me this article a week ago. I fell for it until the bottom. In small print: "April Fools"
 
I can hardly wait sit to see Ricks new hunting truck. I call dibs on picking the berm after he fires a few round of cast from that thing.