Willie made a comment about spare/back-up parts for a 590 in another thread (ejector/screw, shell latch, and interrupter) which prompts me to ask the question. Any other parts worth putting back for the Mossberg 500/590 series of shotguns? Which parts are most prone to breakage/wear and in what way? What needs keeping an eye on? Any commonly overlooked places that need lube?
I gotta say, those shotguns have a reputation for being kind of rattletraps, but the three(!) I have recently accumulated mostly feel like the pump is riding on ball bearings. They are by no means "tight", but when running the action, the reciprocation of the pump is very smooth and satisfying. This is across an 835, 500, and Shockwave. The 835 has the "best" action with the Shockwave having the stiffest. These two also have the most and least rounds through them, respectively.