I’m interested to hear what worked.....
I would do the Kroil (spooky stuff), and the heat treating - heck I’d shoot it to shock it as well once it soaked in Kroil...
***. Stand the gun on the barrel and soak the choke in the solution
A couple things I didn’t hear
1) Use a brass hammer and hit the choke wrench when it’s on the choke to shock it loose.
2). Heat with a blow dryer as hot as you can get the barrel but have some metal on the choke tube to try to keep it cool.... then shock it with the brass hammer.
3). If it’s a remington - they used to make a socket tool with 4 ears for stuck chokes, I haven’t seen them for a bit but they work good.
4). Brownells has a stuck choke removal tool...
there is a video of using an easy out on youtube... not sure how safe that is to do..
https://m.youtube.com/watch?v=2baneo4rgUA