There are a few posts on firearms transport cases on the forum - a search for Pelican cases will get you to many. I recently ordered two cases to transport a take down shotgun. It would also accommodate a disassembled AR type modern sporting rifle.
I first ordered Calebas Molded Takedown Case, IK-23-1098 on the basis of the price and features. It is here http://www.cabelas.com/product/Cabelas-Armor-Xtreme-Molded-Takedown-Shotgun-Hard-Case/1318398.uts?Ntk=AllProducts&searchPath=%2Fcatalog%2Fsearch.cmd%3Fform_state%3DsearchForm%26N%3D0%26fsch%3Dtrue%26Ntk%3DAllProducts%26Ntt%3Dmolded%2Brifle%2Btakedown%2Bcase%26WTz_l%3DHeader%253BSearch-All%2BProducts%26x%3D10%26y%3D12&Ntt=molded+rifle+takedown+case&WTz_l=Header%3BSearch-All+Products. It was $159 plus tax and shipping.
Shortly thereafter, I found the iM3100 Pelican case on the OpticsPlanet website at http://www.opticsplanet.com/storm-case-im3100.html. It was $185, but with free shipping and no tax. It was also featured in a video on how to cut out the foam interior at http://www.opticsplanet.com/howto/how-to-prepare-a-gun-case.html?nldata=563/13/856f87c3a73029fc7b405141ef559a3c&&utm_source=newsletter&utm_medium=email&utm_campaign=howtoguides13.
I ordered the Pelican case based on my previous experience with them and the nominal fee of $7.50 that Cabelas would charge for a return.
Either case would be suitable for hard duty in the back of a pickup or left to the tender mercies of baggage handlers at the airline of your choice, but I ended up keeping the Pelican and returning the Cabelas. Both are virtually the same size, but the Pelican is a little over a pound lighter. In addition, the Pelican has six latches (four on the long side and one at each end) that require a central button to be pushed before they open. The Cabelas has two latches only, but they are metal and of the twist to unlatch type - in my opinion a better latch than found on the Pelican, but they only secure one side. Similarly, the Pelican has four hinges on the side opposite the latches, while the Cabelas has only two. Both have handles on the long side and top, both have equalization valves, and both have wheels. The Pelican wheels are the common skateboard type, while the Cabelas wheels are wider and a little smaller in diameter.
Now I need to get a couple extra pieces of foam so that I can custom fit several firearms.