Look at that action and how thick the corrosion is around the fences and Rockdoc is worried about buggered screws?
Someone took one of the finest shotguns built on this planet and turned it into tomato stake.
It's not untypical to have heavy corrosion around a ML's fences (and percussion nipples), that's where the corrosive detritus from the percussion caps is deposited when shooting. It's not something that'll necessarily make the gun unsafe. Interesting how my comment about buggered screws, taken out of a generic freshening-up-your-gun write-up I did 3 years ago, would be focused on here.
And God forbid someone would want to turn it from a tomato stake back into a useable shooter again. Holy Mary Mother of God, may the saint's preserve us!
Steve