It took me awhile, but I figured out sniping.
DICE are a devious lot, indeed. Do read if you've been having trouble adapting to sniping coming from Bad Company 2 or Battlefield 3.
How sniping has changed.
More so than Bad Company 2 or Battlefield 3, sniping takes skill in Battlefield 4. Bullets in the former two games would travel in a predictable arc, and therefore you would aim slightly higher than the intended target the further away you are, and lead shots to account for bullet travel time. That shit's changed.
In Battlefield 4 bullets reach a distance after which they seem to lose effectiveness. There's an arc, but after a certain distance the bullet plummets exponentially to the additional distance travel. Also, at least it seems, different weapons have a more diverse spread of bullet travel times, also complicating sniping.
You need to learn how to effectively zero your scope. Sniping from one flag to another is usually a distance of 200m, so you should have your scope set to that. If your target it closer than 200m, then you should aim accordingly below their head to hit it. If they are further than 200m, then you should aim above their head to hit it. This is the usually engagement range. 400m is useful for targets that are barely visible unscoped, and I've yet to make a 1000m shot. Make not of the flag distances, they are shown when you aim at the letter representing them. Eventually you'll be able to gauge distances independently.
So, if you are sniping at someone fairly close (where the target is less than a flag away) no zeroing is necessary. A fairly distant target should have the sights aimed just above their heads for a headshot. At most close ranges (below 100m) just aim at the head to hit it, and try to hit the head rather than hit the body. You need to kill them before they kill you, so stand still if your target is aware of you and take cover when possible. Strafing will make a sniper's job more difficult, but it won't significantly make someone with an automatic weapon have a hard time with you. It also makes you less accurate when you move and shoot, for all weapons. For all weapons stand still, engage your target, move (especially high fire rate weapons like LMG's and SMG's).
Typical sniping distances necessitate a zeroing range of 200. Really distance targets (such as one who you need to zoom to see the features of) should usually be sniped at 400m. Those are the most useful ranges. Bullet travel time is fairly linear, and something you'll get a feel for after sniping for a while. Typically, to hit a 200m target moving horizontally I'll aim at where they'll be in a just under a second. For 400m, 2-3 seconds.
Not having a spotter, as a real sniper would, makes these realistic additions to sniping more difficult to contend with. You need to calculate the ranges, and adjust your own shots. However once you get the hang of it, and realize that zeroing your scope is necessary, it becomes quite natural.
