I have multiple ML's with threaded breech plugs. Savage MLII I use smokeless powder), CVA Kodiak, Traditions PA Pellet. I use anti seize each time I reinstall the breech plug. I always hand tightened the breech plugs and did not wrench tighten them. I sometimes have shot as much as 20 rounds before cleaning and have never had an issue removing the plugs.
If the plugs thread easily into the breech and are lubed there should not be an issue. A hot load or multiple hot loads can cause
over expansion. Also, alignment issues can cause galling of the threads.