As I'm his clan mate, I have to post in his defense as he cant come to forum.
Ok. In the first case, many of the players can be knocked down like you did. It's not any kinda of widescreen. It happens to me sometimes also when someone try to shot me like this and I knock him down with spas or any other shotgun.
In the second case, it happens oftenly that when you shoot someone and you see that his hp is like to die but after he stands up, he wouldn't die. And how can you say that his hp was accurately 50? It can be possible that the hp was above 50 like 51-56.