Update - just got back from a trip to Portland, OR. I swear that commercial airplanes are germ factories! Been sick with the crud ever since I got back.
At any rate - check in at RDU was straight forward. I declared the firearm, filled out the tag, and they put the bag on the conveyor. Done.
In Portland I expected to have to go to the gate agent, but the bag came out on the standard carousel.
On the return trip, declared and filled out the tag, and had to then take the bag over to TSA for manual search. Then they put in on their conveyor that apparently bypasses the normal scan.
In RDU, Delta has changed their process and you no longer pick up from the gate agent. Rather you pick up from the oversized luggage window.
Delta now tracks bags with declared firearms. I could not use remote check in in Portland (I could in Raleigh), and as soon as I checked in the gate agent already knew that I was traveling with a firearm.