I have 3 500'some and like them.
http://www.brownells.com/shotgun-pa...517.aspx?avs|Manufacturer_1=VANG+COMP+SYSTEMSat 10:40 he says that the Mossy 590 has a metal safety, whereas the 500s have a plastic safety. I had the plastic safety on my Mossberg 500 break, and it locked the gun in the "safe" mode until I could take it apart and Jerry-rig it. Later I got a new safety. I really should look around for an all-metal safety, if one's on the market.