I've used a 2 gun metal case from Cabela's that I bought in the mid 1990's. It's been from Atlanta to Edmonton for 13 hunting trips and other than a few minor scraps and dents it still protects my gun 100%. My only wish was it had wheels so I could put my duffel bag on top of it and roll it into the airport.
When the African hunt bug hit me I bought a metal 2 gun Safari Case with wheels from Americase. It's great for travel since I use a bungee cord to strap my duffel bag to it heading into the airport. With 10 round trips to Africa, with both the Atlanta to Jo'berg legs and Jo'berg to interior county legs, it just has a few scratches and dirt to show for it.
With both of these gun cases my guns were still zeroed in upon arrival.
Something to note when buying a gun case for airline travel, be aware of the weight. With airlines now charging as overweight a 50 Lbs. bag, see what the combined weight of your new case plus firearms and anything you'll be putting in will be. Most 2 gun cases are around 25 pounds and if you add on the 2 rifles, scopes, slings, extra magazines and locks you'll be getting close to that 50 Lbs. mark. If you're just traveling with one gun you now have room to securely add optics and not worry about the weight.
The padding in your gun case needs to hold your gun securely. Some case have you pluck out the space your rifle will fit which works, but you can also leave the padding in to hold the gun in place by
pressure. A good way to check your gun in the case is to pack it like you're going to for your trip and drop it a couple of times from 4 or 5 feet. Don't baby it, the airline crews surely won't and if your gun moves around from these "Gentle" drops you need to figure out how to secure it better.
Good Luck on your hunt.