I bought an old well used maverick a few years ago. it was one with no vent rib and only 1 slide arm from the pump into the receiver. hunted with it for awhile and it worked/shot fine. since it was my first maverick I didn't see any issues. one day I decided to take it apart to clean it. it was so full of dirt, leaf material, oil build up, powder residue, I couldn't believe it. and it still worked great. once clean and put back together it worked with almost no effort to pump the action. I should have kept it cause it was a light carrying gun. but I traded it because I wanted vent rib and choke tubes. got a 20 and a 12 maverick now. good guns i'd say