Here are two videos I just happened to shoot showing erratic ejection and both videos include a stovepipe. Each happened within 50 rounds of each other.

Late 2010 Gen3 19. Gun's run flawless for about 4K rounds. The descriptions in the videos have some more information. To summarize, this is my daughter and the stovepipes only happened with her shooting. I just got pinged in the forehead a bunch.

"Limp wristing"? You decide.

http://youtu.be/RtVcaR5v4QY
http://youtu.be/O8WIqW-GRms