This occurred immediately after his passport was stamped, indicating that it actually took place at immigration, not customs. (At almost all airports, you go t

This occurred immediately after his passport was stamped, indicating that it actually took place at immigration, not customs. (At almost all airports, you go through baggage claim after immigration (but before customs, obviously). So the bullet was probably carried on, and thus went through security, but small items like this are missed all the time in the x-ray scanner.