A common problem with new shooters or service members is holding the handgun to close to the face. With a semi auto pistol, it can be painful!
I had a US Army MP Sgt in my unit tell the story of a young 2LT who had a M9 slide smack him in the face. Stupid!
Part of the problem is that people watch TV shows or movies then think they can do the exact same. When they twist a semi auto to the side, you know they watched to much of The Wire on HBO,