Yes, the exact same thing happened to me a while back, what has happened is that the finger that is part of the external barrel (Part #312) that is meant to take the BB from the magazine and place it in the barrel has broken off. Here i have some pictures of mine: http://i.imgur.com/ZHTPNh.jpg http://i.imgur.com/H2qYbh.jpg
you can see in the first picture where the metal has snapped, just to the right of the gas nozzle, and on the second picture, where the finger should come all the way out to the same distance as the nozzle. All you need to do is to is to buy one of these: http://store.kwausa....assembly-1.aspx
and replace it. It is surprisingly easy, if you want i could do a quick picture tutorial..?