GarrettJ, when you say "Delta usually does not send my case out on the baggage carosel.... are you talking about an obvious gun case, like a rifle case? Or did they send your regular normal looking suitcase, with checked handgun inside...
I don't ever put a gun case inside a regular suitcase. I go the complete opposite direction. I use a large, heavy Pelican case, even when I'm bringing a small handgun. My large case is not an obvious "gun" case. It looks more like an equipment case (I think it's a model 1720). But I'll put a handgun in there, along with my clothes, laptop, and other stuff.
Think of it this way: the airline does not track your case. They track the
tag on your case. So say you lock your blaster in a pistol case, and hide that inside a suitcase. Now if your suitcase breaks open in Atlanta when you're changing planes and the gun falls out, they have no way of knowing that. They don't know if your gun case walked off at your departure airport, at your layover airport(s), or at your destination. All the airline can tell you for sure is when and where the tag was scanned.
So I want the tag on my actual gun case. I'll use a gun case to carry my luggage. Not a luggage case to carry my gun.
To 9mmepiphany's point, the zip tie does not signify the case for special handling. But they do have ways to do that too. Delta has a "CAGPT" code, which stands for "Check And Give Protection To" (yes, I just looked that up). They used to put a big sticker on the case. In recent years, it is just printed on the luggage tag. But as noted above, it means they pay more attention to it as it is handed off from one place to another. They also make you pick it up at the luggage office, and not at the carosel, where anyone could grab it. Those usually get there after the carosle luggage is all dropped off, so it takes a little more time at your destination. I find the trade-off is worth it vs. the risk of your gun walking.