Just as flyers are getting used to the idea that pilots can carry guns in the cockpit, some security experts and pilots are raising a new concern: What about guns not in the cockpit? The Transportation Security Administration demands that when pilots are passengers, their guns be placed in a lockbox and checked into the cargo holdfully loaded. This flies in the face of the usual law- enforcement practice of not separating man and gunas well as a 22-year-old aviation-safety regulation that requires all weapons to be unloaded when put into the baggage compartment. Some baggage handlers are reportedly refusing to touch the gun boxes. Says TSA spokesman Robert Johnson: "It is safer to minimize handling the gun." If changes prove necessary, he adds, the TSA will make them.