Iowans should press presidential candidates for their views on assault weapons in light of Wednesday's shopping-mall massacre in Omaha, a national gun-control advocate said Thursday. Most Democratic candidates support reinstating a federal assault-weapons ban that expired in 2004. Most Republican candidates oppose reinstating the ban, saying it was ineffective. Paul Helmke, president of the Brady Campaign to Prevent Gun Violence, said Thursday that the 30-round ammunition clips Robert Hawkins reportedly used in Wednesday's shootings in Omaha would have been illegal to purchase under the assault-weapons ban. Helmke said it was not clear whether the gun itself, described as an AK-47-style...