Usage Discussion of HONE IN
The few commentators who have noticed hone in consider it to be a mistake for home in. It may have arisen from home in by the weakening of the \m\ sound to \n\ or may perhaps simply be due to the influence of hone. Though it seems to have established itself in American English (and mention in a British usage book suggests it is used in British English too), your use of it especially in writing is likely to be called a mistake. Home in or in figurative use zero in does nicely.