Slipping on idioms and phrasal verbs

Although I’ve never heard anyone say #21, it means you’d be back where you started if you made a 320 degree change. Here’s some detail on Home In and Hone In. I’ve always said this the “American way.”

Home in means to direct on a target. The phrasal verb derives from the 19th-century use of homing pigeons, but it resurged in the 20th century to refer to missiles that home in on their targets. It’s also commonly used metaphorically, where to home in on something is to focus on and make progress toward it.

Hone in began as an alteration of home in, and many people regard it as an error. It is a very common, though, especially in the U.S. and Canada—so common that many dictionaries now list it—and there are arguments in its favor. Hone means to sharpen or to perfect, and we can think of homing in as a sharpening of focus or a perfecting of one’s trajectory toward a target. So while it might not make strict logical sense, extending hone this way is not a huge leap.