I don't no but I have only been playing this game now a couple of months, and after a long hard struggle have worked my way up to a 42 rank, but its been hard and frustrating at times, and is now getting to the point where I am thinking of just packing it in Reasons
(1) Hardly any servers playing classic, its the easiest for me to play
(2) come face to face with enemy both shoot at the same time they win ever time
(3) watch the kill cam and one bullet kills me from miles away,
(4) I have to unload a full magazine to kill someone,
(5) Getting killed on respond,
(6) About to make a kill and someone shoots you in the Back,
(7) Always seem to be in the wrong place at the wrong time,

Its just goes on and on, I believe I may be lagging it so hard to make a kill, my ping is above the average of other players in the server I play, The only one team ru Moscow or something, Is there no UK servers playing Death match, I only play classic because in standard you cant even see who's coming at you (cloaked)
Maybe I'm just crap but that red dots Right on the enemy ful magazine later they might be dead.