I use 50% less priming sugar and it works fine. Make sure to purge the keg (although I suspect this isn't all that important when naturally carbing) and hit it with high pressure to seal the lid. Then it's just a matter of waiting until it's ready to drink.
Kegged: IIPA, Vanilla Porter, Herbitude 3, Berliner Weisse, West Coast Red (Red IPA?), 80/-, Trippel, IPA
Bottled: RIS II
Primary: Robust Porter, India Brown Ale