I'm not sure it every was a ctg. I know I saw it in my first COTW, way back in the early 70's and thought WOW - then read some time later, is was a spoof, someone made up.
Quite possibly someone barreled up an action for it, but a rifle made by Winchester, I just don't know?
If so, it is not listed in any of my Winchester books.
It would have to have been barreled up and chambered, perhaps in one of the 10 bore 1887 Winchesters, I would imagine.