For those having issues on how to aim accurately with the iron sights, see the below images:
Imagine the red dots are heads, or whatever you wish to hit. Up to 200m you should not have to adjust your sights. Place the tip of the front sight over what you wish to hit, like an arrow saying "put bullet here" and fire away.
However with some weapons, due to recoil, the sights are a bit different when it comes to hitting what you want. As an example, take a look at the PPSH:
The recoil and rate of fire causes the aiming to go all over the place, even when controlling the recoil with the mouse. Place what you want within the sight hood area shown, like a picture frame.... and then unload. This also works in the same principle as the MP40, but since the MP40 has a slower ROF and recoil, the accuracy is a bit better.... still, place what you want within the sight hood, rather than using the tip of the front sight.
The DP28 also has an odd way of aiming when it comes to getting an accurate shot off:
Again, imagine the red dot is the target you wish to hit. Use the central area noted by the front sight and the two curved spots of the sight as a centering point and fire away.
With Full Auto weapons, Burst shots are the best way to maintain your accuracy, as well as your ammo.
Here is a basic break down of the various spots on each tank in RO2:
• The Yellow areas are for damaging various parts of the tanks, perhaps disabling them
• The Orange areas are where you try to take out crew members in each tank (not always easy to do)
• The Red areas are where you want to aim in order to do some serious damage and possibly blow em up.
If you just want to know where the easiest spots are to blow up a tank in as little hits as possible, see these two diagrams:
Hit these areas with your tank's AP rounds for a quick kill, or a couple of times with an AT Rifle at close/medium range for a kill.
If you are using an AT Rifle and too far away to do much damage to blow them up, there are specific areas you can hit to either take out the brakes or at least cause the player in the tank to get freaked out that they're going to die as their tank AI start screaming about taking damage. You might even get the tracks:
You can hit these areas at any distance and you will see impact damage (a flash explosion, rather than a black puff) which will either cause damage, or at least make the player's AI crew think it is and make the player in the tank either move from where they are (if they are pinning down your team) or distract them long enough as they look for you, allowing another team mate to come up behind with a satchel or AT grenade (or allow your team to get out of there)