with the sniper rifles (any of the single shot ones) you can jump while zoom, and as you land, still have perfect accuracy, its a bug they still haven't fixed, the shottie, the non-auto, and close-mid range a headshot is 99% of the time fatal due to the buckshot spread (with helmet) without, rare as heck, you can kill out to medium range, the silencer for the m4 is something i like. Burst fire, always with the rifles, it takes getting used to, short bursts are 2 bullets, normally long range firing. or a longer burst of four, at closer range. it helps keep accuracy so well once you lean that. (i stopped playing after learning the sniper zoom bug and it still hasnt been fixed so i wont play unless they do.) I doubt they ever will.