A 51-YEAR-OLD American citizen was yesterday sentenced to nine months in jail for travelling to Hongkong with an automatic pistol and 50 rounds of ammunition in his luggage. The court heard that Arturo Balbago Custodio arrived in Hongkong with his family on March 29 on a flight from Los Angeles to the Philippines. He and his family had to stay overnight in Hongkong because their flight was delayed. When Custodio checked in to travel on to the Philippines, a luggage scan revealed that he was carrying a nine-millimetre calibre automatic pistol and 50 rounds of .38 calibre bullets. Defence counsel Mr Steve Chui urged the court to consider Custodio's plea of guilty, his clear record and the fact he was remorseful. Deputy Judge O'Donnell said: ''The defendant clearly is not in a position to pay a substantial fine.'' He said the only appropriate way to deal with him was with a short custodial sentence. He added: ''In my view, there is a clear warning on airline tickets about such offences as carrying firearms on international flights.''