The only maintenance to my 391 I had done since 2003 was just pull the barrel and swab it out good with whatever solvent and oil I had on hand, and a general wipe down of light oil across the whole thing for storage. This spring was shooting sporting clays with a buddy that had bought one at the same time, he commented on how slow my action was closing when the 'close' button was pushed. I hadn't noticed it, and it wasn't causing issues on repeat shots as it was faster than I could get on the second target. I went home and did a complete strip down of the gun to its component pieces. All kinds of brake cleaner were used and a stiff nylon brush. put it back together and it liked to have ripped my finger off that was in the way when I pushed the close button.
The innards were filthy after 5 years, but still functioned well with no jams. Now it still functions well, but a little faster.
