I'm new at this and a little confused. I unscrewed the magazine cap and exposed the magazine spring. The owners manual indicates that there is a "magazine spring retainer". As I look into the magazine cap, seated in the cap is a plastic fitting. Is that the "retainer"? The manual seems to indicate that retainer seats over the spring into the magazine tube, then the cap screws on. Am I missing the "spring retainer" or just misunderstanding the manual? I can say that everything worked fine when I shot 15 rounds earlier at the range and after I reassembled the barrel everything seemed to work as before. Thanks from a newbie!