@ Ext3rmin4tor
Also, just for general information, air resistance on a projectile is negligible. Of course, in RL it will play some slight, minuscule effect on the velocity of the bullet, but bullets are shaped in order to decrease this effect (minus wad cutters, if you are familiar with them). Now, that being said, a bullet in flight can easily be susceptible to wind, because the side profile of the round is not shaped to decrease wind resistance on it. Therefore, on a windy day, the accuracy of your shots will be skewed because the round is pushed by the wind.
What affects your accuracy the most is gravity. If anyone cares to have them, I can scan the charts I have for zeroing. But the short of the long is, when zeroed with iron sights by US Army standards (a 25/300 meter zero), due to the arched shape of a projectile's flight, if you were to aim center of mass at a target 500m away with an M4, your point of impact would be about 65 inches below the target. If you were to sight your irons by USMC standards of 36/300 yards, the point of impact when aiming at center of mass at 500 yards would be 49 inches below target.