I bought a Cabelas two gun aluminum case twenty years ago. There is room for two scoped rifles, binos, knives and my shooting stick. It's flown out on 25 trips; I once saw it fall off a conveyor, fell 6 feet to the ground. It never scratched the case or the guns inside. I've never had to adjust my scope at my destination. My buddy got an updated version of this case, his has rounded corners and wheels so you can pull it through the airport.
Whatever you decide on, Pick out the best you think you can afford. Then buy one a grade better. Never, ever, ship in a plastic box. I've seen too many Dsports and Walmart boxes busted up at the baggage carousel. I think some baggage handlers enjoy banging up gun boxes.
Pelican 1750. If your careful you can fit two guns. Plenty of padding for one. Lockable. Airline approved. Check with your airline as well to verify approval. Rolling wheels. Good to go. Be careful when buying. Make sure you opt for the case with the foam. Because they can be purchased for much cheaper with out the foam. I almost made that mistake. B and H photo has the best prices I have found. 210 for green with free shipping.
WAIT! WOW 179.99 on sale at Midway USA!!! But there are shipping charges that bring it to 206.00, but with this 10 dollar off code, down to 196.00 you go
I prefer SKB to Pelican cases. SKB warranties the contents against damage or loss (up to $5,000, as I recall). They have TSA locks, so you don't miss your flight returning to check in when TSA decides to finger your firearms (again)...if they even tell you...after you've already gone through security. When TSA pries off your TSA-compatible lock (happened to me three times), SKB will FedEx you (at no cost) new locks/latches that are user replaceable with nothing but a screwdriver. I've traveled all over the world with my issued Pelican cases and weapons, but when I'm traveling on my own, and with my own firearms, I use SKB.