I often travel with valuabel OU tube set guns.
Its not a big deal and my experience has paralleled some of what is posted above.
1. You gun must be in a lockable, approved case.
2. Take your luggage and the cased gun to the ticket counter, you cannot use curbside check-in for your gun.
3. Tell the ticket agent you have an "unloaded firearm" to check. I strongly suggest you don't yell, "I have a gun". Just a little common sense works wonders, eh?
4. The ticket agent will give you a small card to fill out with your flight info (they often fill that part in), your contact data, and your signature.
5. You then open the gun case and put the card in. When in doubt, just be open and ask. Example, "may I lock the case up now, Miss?" The ticket agents are interested in inspecting the gun, that's TSA's responsibility.
6. At this point, procedures vary a bit. In some airports (like BWI) they take the gun and put in on the conveyor and TSA processes it in the bowels of the airport. In many, you may then be instructed to take the gun to a TSA table/x-ray machine and they may make you open it again and check it over. At Islip airport on Long Island, you need to take it to a table where TSA and a local cop check the gun and then make you lock it. From there its out of your hands.
7. At your destination, it may come out with the rest of checked baggage, but often it goes to the airlines baggage service office with the oversized stuff like golf bags. This varies, so when you get there, go to the office and ask then where it will come out.
8. Federal law allows you to have up to 11 lbs of FACTROY BOXED AMMO in check luggage. I have never put it in the gun case, and I suggest ou don't either. Seperate the ammo from the gun, don't give anone a reason to get excited. Not just factory, but in the factory box. No extra shoot off-shells in a plastic bag. I persosonally do not know of any airline that does not honor this Federal regulation.
Cheers