Near the end of the the film where there is a gun fight where he is fighting guards every time the camera goes off him and on to the guards he has a different clip in his gun a rounded and a flat clip.
When he first enters the hallway he slides two extended clips with large bulbous ends down the hallway. After he gets about 2/3 of the way down (after he uses his sleeve auto-reloaders) he puts his guns down on the extended clips. Those are the clips you are seeing. They have more shots so he uses them to fire in full-auto mode.