The National Rifle Association is opposing a ban on “bump stocks” like the device used by the Las Vegas gunman, stressing its support for more limited regulations. The powerful lobby last week surprised many gun control advocates by embracing possible restrictions on the bump stock devices in the wake of the shootings, prompting bipartisan support in Congress for regulating or banning bump stocks. But on Sunday, the NRA drew a line on an outright ban. Chris Cox, the NRA’s chief lobbyist, said it was the responsibility of the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives – not Congress – to regulate the sale of bump stocks.