Success! While I may not be very creative, I am
pretty good at following illustrated instructions per the aforementioned thread. And as I halfway expected, there was an audible crack when it finally broke free. Yes, there was a little overspray inside the receiver, as well as the external barrel/receiver junction that left a little ridge after separation.
No problem, a 12 ga shotgun brush and then spinning the barrel while pushing in and pulling out smoothed everything out nicely.
Oh, and also applied Aeroshell MS33 grease to all the steel/aluminum interfaces, as per my AR training.
I'm glad that's done. And I'm glad I probably won't have to do it again...