This topic may not interest too many folks, but my favorite hard rifle case for travel is a Tuffpak. It looks like I am traveling with golf clubs, and it is a very strong and reliable case. My case has been many thousand miles on airplanes and has a lot of travel scars, but no damage at all. One thing that I think help is the shape - it is not flat so the baggage apes don't stack it on the bottom, and it would be hard to throw.

The model I use takes a padlock (TSA lock if required). I can put two scoped rifles in soft cases in it along with a few other items and still be under the 50 pound weight limit that most airlines use.