Empty mag would work except to me that is very much against how I was trained to clear a weapon. It sounds like you're a righty so try this. Instead of gripping the slide with thumb and first finger from the rear of the slide and the rest of your hand not doing anything.. Hold the gun in your strong hand and bring the gun across your body and grip the slide with all of your weak hand (keep your palm out of the ejection port, it could give you a not very playful pinch). Use both arms pushing in opposite directions to work the slide and hit the slide catch lever with your strong hand thumb.
Edited to add: Just like the video in the post right above mine.
Last edited by Habaz72; March 25, 2013 at 01:30 AM.