If shot, moisture hunts or won't be using it in the near future it is cleaned. If unshot, dry and will be using it the next day I keep it loaded. If ever unsure I error on the side of caution and clean it, this way their is no doubt it will be ok.

There really is no reason to keep your ML loaded during the off season, minimally you should do a tear down clean once a year to ensure rust or pitting does not form in area's you can't clean or protect with casual cleaning procedure's.