Just feel I need to pop back in to this post to hopefully give some useful advice and save somebody a nasty experience.
Jeez. Always used to put chokes in with just a little oil on the threads. Never had an issue, loads of guns over 20 years. Last time, I used some proper Teague grease on my 694. Thought I’d take chokes out today for a routine clean. I knew they weren’t stuck tight so had been happy leaving them in for a long time, probably 7000 shots as I don’t change chokes. What a nightmare just now. They unscrewed with a firm twist, but what a sight. Threads coked with a nasty hard crust. Took ages to clean it all up with various chemicals, brushes and finally a steel pick between threads. Won’t use grease again. Perhaps the Teague stuff is the worst, or maybe all greases break down in a barrel and go nasty over time. Oil for me!