Get the Harddigg Storm, preferably the 3300, thats the longest + made for 2 rifles (hunting rifles). I have one for my AR, at first it may seem like too large of a case for just an AR, but as we all know AR's tend to sprout little offspring accessories and attachments, so you might as well get the space to expand. Mine holds my AR 20" HBAR with a large 50mm scope, 4 - 20 rnd mags, 4 30 rnd PMags, Paddle holster, Bipod, full size cleaning kit, XD9 w/ 4 mags, and KBar, and STILL room to spare. I will be adding a 16" upper in there to round out the kit cuz there is that much room as long as you plan ahead and utilize the space well.
There is no question that if you want to go all out on a case go for the Storm. Storm cases are usually slightly cheaper than Pelican's, although Pelican recently bought out storm so who knows now.
Though almost the same size and same features, Storm 3300 wins out on the Pelican 1750. Storm has 2 extra latches on each side, Pelican doesn't. Storm is also waterproof, meaning it can be submerged, while Pelican is water resistant, does really well in wet weather but cannot be submerged. During Katrina there was actually a police unit whose gear was in a Storm submerged in their cruiser in salt water for 2 weeks and was bone dry when they retrieved it. Both cases you can take on a plane because of the padlock holes.
The Storm comes with 4 layers of dense foam and if you cut it correctly, you have a fitted, superbly protected, waterproof, shockproof, rust proof (as long as the seal stay tight and maybe add some silica) case that you can toss in your truck or take on a plane.
This guy is probably the best and his was a do at home, "mfingar" on AR15.com, it's how I learned how to do mine, Planning and patience is key.
this is just another random one.
***Oh and how many Mags will it hold? as many as you can fit!