The city of San Jose has outlawed the sale of realistic toy guns to prevent "tragic incidents" like last February's San Francisco police killing of a teen-ager. The City Council adopted a law banning the sale, manufacture and distribution of realistic replicas of handguns, rifles, shotguns, automatic weapons and rocket launchers. It is virtually identical to proposed state legislation. Similar bans are in effect in Los Angeles and Burbank. Oakland is considering such a proposal. "I think this is a common-sense action we can take to prevent the kind of thing that happened in San Francisco," said Councilwoman Susan Hammer, who proposed the law. A 13-year-old boy waving a toy plastic pistol was shot and killed by police at a San Francisco housing project in February.