The phrase [hone in] seems to have become established in American English, and is apparently beginning to be used in British English (Garner has a British example). If you use it, you should be aware that some people will think you have made a mistake.Not surprisingly, the folks at Language Log have have also discussed it quite a bit. One of the interesting things is that though the verb to home has been around a long time, home in and hone in are both recent coinages. None of which is meant as a serious defense in my particular case, by the way; had I noticed it, I would have certainly chosen home in in preference.