I came up with this character that goes for one big shot per round.
Tiefling or Elf Ranger(freebooter)X/Unarmed Fighter1. Focus on dexterity and intelligence for your stats, keep wisdom at 12 so you can pick up gravity bow. For combat style grab Focused shot at Lv2 and Crossbow Mastery at Lv6 using the alternate ranger styles. Unarmed fighter allows you entry into Kirin style and you get Kirin strike at Lv9. Feats should be the basics, point blank shot, precise shot, deadly aim. Use the biggest, baddest crossbow you can find.
Your combat rounds go something like this; swift to identify your target, move action to activate freebooter's bane, standard action to fire crossbow with kirin strike, focused shot, deadly aim, and freebooter's bane all tacked on. The combo of kirin strike and focused shot alone nets you intelligence x3 to damage.
Another bonus of the build is 6+int skill points, good HD and Bab, a nice set of passive abilities, and team support. Makes for a great Sniper or Hunter style character.
You could drop the unarmed fighter for 2 levels of Master of Many Styles and get better saves, a few more skill points, and access to Kirin Strike earlier. A level of alchemist could get you a mutagen for more stat increases at the cost of some Bab. Depends on how min/maxxed you're looking to go. Also ask your DM if vital strike can be used with Focused shot, they're both standard actions but the wording is awkward.