The reviews seem to point to Pelican making a good rifle case.
If you plan on flying with it, i noticed some mentioned being TSA approved and some did not mention being TSA approved. The main thing is that it can be securely locked.
Also these cases weigh like 20-24lbs empty, So its a pretty safe assumption that its sturdy enough to survive any abuse it might experience.
Also because it will probably weigh 30+lbs with a gun in it, consider a case with wheels if you don't feel like carrying around that sort of weight. All depends on your situation i guess.