Since Jan1 I have flown 4 legs on Delta, 2 on Alaska and 1 on Southwest, all of them with a firearm in checked baggage. My experiences vary widely with each airline, but with Delta it varies from airport to airport. In Seattle and Las Vegas, I've been asked to open my case to verify that the firearm is unloaded. As if they have been trained to really verify this. I've shown them that my Glocks have no magazine in the magwell, but never shown that there isn't a round in the chamber - again, as if they want me lifting the gun with two hands, I can open the slide. In Phoenix, the Delta attendant said, "No, I don't want to see inside the case. We're not trained for that, and that's why we have you sign a card that states the gun is unloaded". This seemed like the best and most reasonable answer I've heard. My experiences with Alaska and Southwest are the same as this last one with Delta - "Just sign the card, and we're good...".
Delta puts a CAGPT sticker on the bag, with stands for "Check and Give Protection to" which seems like a "This bag has something worth taking" sign. This means that it doesn't go out on a standard carousel at the end of the flight. When I picked up my bag in Vegas, it had a series of heavy duty zip ties locked around it, length and width wise. I asked if they would remove them, and they said it was there policy (since late January apparently, since it didn't happen in early January) to not allow them to be removed until after you left the airport. I told them my multitool to remove them was inside the bag. They didn't care. So I walked around the airport (an airport that allows open-carry without permit, by the way), and to the rental car pavilion, with a bag that screamed, "I've got a gun inside, come try and take it from me". I thought that if it was zip tied during the entire flight, at least that makes it more difficult for some baggage handler to get into it while it's outside of my control. My return to Seattle showed me that this isn't the case. I was at the "special pickup area, when the bag arrived - unzip tied. The local agent (who kept apologizing for the stupidity of the act) was forced by Delta policy to zip tie it before she gave it to me. So, This is Delta's way of saying, "after a year, this is how we are doing our part to make sure a Ft. Lauerdale type airport shooting doesn't happen." It's ridiculous, really.
As for Alaska and SW - it has extra identification tags, and has to pass the TSA extra screening. However, once at the destination, the tags are removed and it is placed on the standard carousel, like normal luggage. This seems appropriate - and I make sure I'm at the carousel when the bags start coming out.
So, your mileage will vary depending on the airport, and the particular representative you get. There will most certainly be aspects of the process that don't pass the "basic reasonable" test, but so far my firearms have ended up in the right place everytime. Guess that's the PC world we live in now days.