That gun you depict is suffering for poor or long term storage among other things IMO.
For reference, I know know for a fact that this pistol isn't suffering from long term storage in anything but a holster (in a relatively dry climate). It came from a duty belt into my hands.
Ask one of your many, many retired LE / bodyguard / coffee shop buddies about the rust line on these magazines.... As they sit in this picture, what would that rust line coincide with?