While I'm all for reducing smuggling, it's naive to think that closing down one "loophole" will have any meaningful impact on the number of illegal guns brought across the border. Guns are extremely easy to smuggle. An unloaded gun cannot be sniffed out by dogs or detected with chemical sensing equipment. A few handguns hidden among a truckload of goods will never be intercepted at the border unless you have specific intel about a particular vehicle.