you are pretty much good to go! I just got a cheap hardsided case that locks at big 5 sporting goods, nothing fancy, but it will easily hold 2 full size pistols or one with accessories and ammo.

Also, they will probably open your bag just to make sure that the declaration slip is properly placed in/on the firearm, and to make sure it is actually in the case, so make sure you get a TSA approved lock for you suitcase, or else it they will cut off your lock and not put anything back on it... not cool! On the firearm case itself though DO NOT USE A TSA LOCK ON THE FIREARM CASE, AND MAKE SURE THIS IS A LOCK WITH A KEY, NOT A COMBO, AND THE ONLY KEY IS IN YOUR POSESSION, NOT IN THE BAG!!! If they want to open the firearm case, they will page you and have you come open it yourself. Much better than some sneaky TSA dork getting himself a nice XD for free, and you having no proof who did it!

The whole process was super easy and painless. Pack the firearm on top... When I checked my bag, I said that I had a firearm to declare in my checked luggage, the lady working the counter gave a few quick keystrokes, asked me if it was unloaded and if any ammo was in the original boxes. I said yes, she handed me an orange tag and said to put it in the box with part of the tag/string hanging out, relock it, and put it back in my suitcase. If TSA had questions, they would call me over the loudspeaker, so keep my ears open! I was never paged, and everything went smooth, unfortunately, the TSA guys did go through my bag that was packed pretty stratigically to protect some valuable stuff from my grandfathers estate, and with things being shifted, the stuff was broken.... grrrrrr!

Hope this is helpful!!!

~Ben