Pelican Storm
Not long ago I needed a good quality single rifle case and bought a Pelican Storm 3410. It was not inexpensive but you get what you pay for with the Nalpak products. I think it was somewhere around $200.
I wanted a good one and could not find a better single rifle case. The SKB cases looked well built and sturdy but the Pelican did not cost too much more and I liked it just a little bit better. It is not lightweight so thankfully it has wheels. It is extremely tough and very well padded.
Baggage handlers are very hard on luggage particularly rifle cases. A few years ago I had a nice double rifle case destroyed by an airline. Luckily the contents were not hurt. These days I usually travel with an indestructible Tuffpak, but this Pelican Storm case is so tough I am not afraid at all to fly with it when I need a smaller case.