Question about a mossberg maverick?

i just got a mossberg maverick 12 guage pump action as a cheap gun to use for the upcoming turkey season on public land since my over under is to nice to risk on a backpack hunt. but when i hold it barrel end up then flip it to end up it makes a metal cling sound like the spring in the ammo chamber is loose ro something. does anyone who has a maverick shotgun do this to ?? is it normal ??? and i havent figured out how to field strip it. my old pump used to unscrew from the ammo chamber but this one has a screw instead of a cap.. any help?