WASHINGTON — The intensifying gun-control debate has given rise to sloppy claims on both sides. Here’s a sampling, with the first two examples from the Senate Judiciary Committee’s hearing on guns Wednesday, and the third from Vice President Joe Biden’s online video chat last week during a Google Plus forum. ___ IOWA SEN. CHARLES GRASSLEY, the top Republican on the committee: “The 1994 assault weapon ban did not stop Columbine. The Justice Department found the ban ineffective.” THE FACTS: The 2004 study conducted for the Justice Department did not conclude the decade-old ban was a failure or a success. The …