If you can't get it with a reasonable amount of force take it to a gun smith, they can probably get it out.

You should anti sieze on your choke tubes it helps quite a bit. I don't put them in real tight to begin with. Most of my guns they come in and out with a quarter, I don't even use a tube wrench.

I know all kinds of methods for freeing up stuck things, but I don't know that I would advise any of them on a gun, especially something as nice as yours.

Paul