“Iowans for the Prevention of Gun Violence” leaders are at the statehouse, pressing for a law that would close a loophole that lets some people sell weapons at gun shows, without a background check.Iowans for the Prevention of Gun Violence president John Johnson says unscrupulous people go to gun shows and claim they are selling guns from their private collection, which means no background checks are necessary. Johnson says all private sales between individuals should be covered by the waiting period for background checks.Johnson says the lobbying trip was planned long before any in his group heard about yesterday’s school shooting in California. He says, unfortunately, it takes a shooting to heighten interest in gun violence prevention.A bill to close the gun show loophole is in the Senate Judiciary Committee.