FWIW, I flew from Atlanta to Minneapolis-St.Paul over the weekend on business, transporting my Taurus PT-145 Millennium Pro with two magazines in my bag.
In Atlanta, when I told the ticket agent I had an unloaded firearm in the bag, she got the orange "Unloaded" card, and asked to see the weapon. I showed it to her, and demonstrated it was unloaded by pulling the slide partway back. Not sure she could see into the chamber, but she accepted it, had me put the tag inside the gun box, then told me to lock the box, which I did, then had me place it in the bag and lock the zippers. She then told me to take it over to the TSA Security checkpoint, which I did. I told the TSA agent about the weapon, and he asked if it was unloaded, did the agent give me the tag, was the weapon inside a hard sided case, with the tag in the case, and was there any ammunition in the case. The ammo was in two loaded magazines in a hard double magazine pouch, elsewhere in the bag. After I told him that there was no ammo in the case, I was temporarily uneasy, wondering if he meant the pistol case, or the bag. Since he referred to the bag as "bag," though, I didn't anticipate any problem. There was none -- the bag went through the X-ray machine, and the guy who took it out pointed to it and asked if it was mine. I nodded, and he put it on the conveyer, motioning me to go on to the gate. No problems encountered.
In Minneapolis on the return flight, I notified the ticket agent about the firearm, and she called over a TSA security officer, who looked at the gun (never checked the chamber), put the orange tag in the case, and locked the case with one of my padlocks. He then put the gun in the bag, zipped it up, locked it and sent it on its way on the conveyer. Again, no problems.
Then, as I was starting to get in line to go through security, I realized that when I emptied my pockets, I had neglected to take out my S&W SWAT automatic knife, which was clipped to the side of my pocket! DAMN! :banghead: Now What!??! I hastily got out of line and returned to the ticket agent, where the TSA guy was still standing. I told them I'd forgotten my knife, and asked if there was any way I could put it in my bag. (Thought I'd probably have to try to find an envelope and mail it home -- fortunately, had plenty of time.) The TSA guy said he remembered my bag, and offered to put it in one of the outside pockets for me. I gave him the knife, and spent my flight home wondering if I'd just helped arm a TSA security officer. To make a long story short, the knife was in the pocket when I got my bag back in Atlanta.
My experience was positive on both ends, with neither the Delta Airlines people nor the TSA officers treating my transporting the weapon as anything but routine. Never was asked about ammo, and no problems transporting it in a soft bag with the zippers locked with a luggage padlock. Just had to be locked in a hard-sided case inside the bag, was all.
