No guys, not a typo, an actual gun, and kind of rare.
The 4596 is a traditional double action stainless with a full-sized frame and a compact slide.
According to Supica & Nahaus, it has a 4506-1 frame with a 4516-1 slide, only about 500 made for special order by Lew Horton in 1990.
It is, like all S&W .45s, a single-column, with a 3.75" barre.