OK, so I do believe I posses a 20MM barrel for the above mentioned aircraft gun. I spent the last 2 hours searching, and am finding not a whole lot.

If anyone has any books with photos of a MG 213 Please add them to this post or a link.
Basically this is like a huge revolver , but loads like a semi/full auto from a cylinder. One single barrel, round is fired into a bushing/forcing cone then into the barrel. But I cant find any good pics or schematics to verify this.

Any help is greatly appreciated.
Snert