So because you're shooting at them they shouldn't be able to kill you? (Stop missing) You have any idea how stupid that sounds? Have you ever been in a real fire fight? It doesn't work that way. I've been in some while taking fire from PKMs and we shot back and took them out.
If you shoot at a sniper in the game then try to be more accurate and scare him into taking cover. Or shoot better and kill him first. The only thing that should be added is concussion from grenades and rpgs that hit close.
And a sniper killing you close up with a 10x zoom is obviously possible if it's happening, no idea how you would want them to change that.
Sounds more like you need to work on how you play the game.