Our Staff Instructor Rick Furr has cautioned about this sort of thing for years. People who keep their hands over the ejection port while clearing a chamber during unloading or malfunction drills have been seriously injured. One potentially dangerous example is with people trying to “catch” an ejected round while clearing the chamber, and has resulted in the primer being struck by the ejector.
In the below article, the hazard is created by a cartridge being detonated without a closed chamber through the use of ill-conceived inert training ammunition.
Please read this article. The author got lucky and was not seriously injured. Others have not been so fortunate.
http://www.qsitraining.net/malfunction-drills-got-little-exciting/