I think Brian has hit it on the head with this. At the end of the day, you can be satisfied in knowing that you took them out before they got you.
Unfortunately, lots of times when you hit people at range( especially with a single shot) they either don't feel it, think they felt or heard it then stop to listen for another, or don't call it because they don't see or hear where it came from.
The Key frustrating part for me is when you are in a milsim setting where a key opponent that you should have taken out (medic or leader) could very easily change the course of a battle or a game.
It's all part of the game. Just play fair and set a good example.