Montgomery County Executive Douglas M. Duncan, a Democratic candidate for Maryland governor, testified in Annapolis last week in support of a state ban on military-style weapons. "I lived through what one of these weapons can do during the sniper shootings," Mr. Duncan said, referring to the shooting spree in October 2002 that killed 10 persons and terrorized the Washington area for three weeks. "We don't need these guns on the streets." The bill by Delegate Neil Quinter, Howard County Democrat, would replace the federal assault-weapon ban that expired in September 2004. It would outlaw the sale or possession of 19...