Check out the Polish wiggle technique:
http://www.youtube.com/watch?v=-RgH6...page=1&t=t&f=b
One more:
http://www.youtube.com/watch?v=O7hi20TI_jA
I usually just take the mag out, set it down, snap another one in there, and run the bolt without all the slapping and blazing-fast arm movement but what the hell do I know?