You could use a Gun Case,
Just don't carry it through the airport.
why? as long as a firearm is in your checked luggage, and you declare the firearm, it's perfectly legal.
although...you are right....carrying it out in the open through an airport might not be the best idea.
"Firearms and ammunition may not be carried by a passenger on an aircraft. However, unloaded firearms may be transported in checked baggage if declared to the agent at check in and packed in a suitable container. Handguns must be in a locked container. Boxed small arms ammunition for personal use may be transported in checked luggage. Amounts may vary depending on the airline. "