I have used SKS hard cases for the past 8 years. They have been abused by airlines, UPS, and US Mail without failure. Not exactly cheap but well worth the money in my opinion.
NRA Life Member
"Democracy is two wolves and one lamb voting what to have for lunch. Liberty is a well armed lamb contesting the vote" Ben Franklin
"The constitutions of most of our States assert that all power is inherent in the people; that... it is their right and duty to be at all times armed." --Thomas Jefferson to John Cartwright, 1824. ME 16:45
"It is Godís job to judge and forgive my enemy, I only arrange the meeting." Unidentified Marine