As a Department of Homeland Security Transportation Security Officer, I will say this: If you prefer to take the upper with you on the flight home, you may want to have it in a durable lockable case of some sort. You can either have it in your suitcase (if you dare) or check it seperately. Personally, I recommend shipping it. It is less of a hassle.
To set the record straight, what gun owners have to fear most when transporting a weapon on an aircraft is not TSA personnel, but rather some of the airline ramp personnel. Trust me, I have been there. For three years, before joining TSA, I worked in the airline industry. I had seen the results of pilferage too often. This was all before TSA ever existed. If someone transports a firearm, they need to make sure that it is in the most secure container possible and have extremely durable locks. The "TSA" approved locks are a POS. Buy "Masterlock", "Yale", or some other heavy duty padlocks. I had a passenger the other day that was transporting a rifle, shotgun, and two handguns in a case that had the little slide-type latches. He only wanted it secured with the cable lock. I wrapped the cable around the handle a few times and secured it. The handle was not going to come loose. However, you could slide the latches open and lift either end of the case wide enough to get everything out. I had to emphasize to him to get a better cae for the next time. At least one that had lock loops on the ends and near the handle. All I could do for him was to tape over the latches and hope for the best. As a responsible gun owner, it is very important to me to have weapons completely secure before they transport.