My experience from NH to FL. this past Feb. was tit. I took my KelTec PF9. Took two small size gun cases. One case had the gun which was unloaded, slide back with one of those cable locks through it. Other case had the empty mag's but no ammo. The ammo I purchased in FL.
Check in counter, told the lady I was declaring a firearm. SHE filled the tag, I only signed it. SHE called over TSA who asked me where it was. Told him it was locked in a gun case which was also in my suitcase which was ontop of the scale right there in front of him. Asked me to show him. I opened my suitcase and then unlocked the gun case showing him weapon. All he saw was that it was both, locked in a case and locked with cable. He asked if I were Law Enforcement which I replied no. He said, "ok". Lady gave me the tag and I affixed it on the gun case in front of them. The TSA watched me then lock the gun case. I asked about me locking the suitcase and he said NO. Needs to be unlocked for security purposes in case another TSA needs to inspect it. From there I was escorted probably about 20' from the checkin counter to the baggage conveyer. There, the lady told the "checkers/TSA" said baggage contained declared firearm in which they proceeded to put suitcase on conveyer and let i go through screening. When it came out the other end they gave the "ok" sign and that was it. NEVER did they ask about the Other case with mag's. Nor, did I mention it. In FL nothing happened there. I waited till I got to my destination before I even took weapon out.
I checked ahead of time with My insurance Co. about coverage on My firearms telling them about the trip asking if they are stolen/lost at the airport, in transit or even from a rental vehicle. My insurance said everything is covered (more detail I won't get in to). I don't want to say I didn't care if they were stolen or lost, but that the fact was they would be covered if said happened. Don't get me wrong, it would suck if it did happen and you read in the paper someone was killed with your weapon! You should be fine...good luck!