If you have scope how hard is it to hit the target?
How far away are you? I'm an amateur at best, and I'll list what you have to compensate for off the top of my head assuming a correctly calibrated rifle, scope and rounds.
Distance - Do you even know how far away the target is?
Bullet trajectory - How far up or down will the bullet rise/fall between the end of your barrel and the target depending on your zero (the range in which you've calibrated your rifle/scope)
Wind - How fast is it going and in which direction? How many different directions and speeds is it going between you and the target?
Target movement - Which direction and how quickly the target may be moving. How much to compensate for this movement for the time it takes for your bullet to reach the target.
Temperature - Warmer air rising from the ground will effect your bullet
Atmospheric pressure - Yes, the pressure effects your bullet
Mirage - Looking through your scope gets blurrier as distance increases and you have to turn down the power. At sufficient distances, the little dot in your scope could cover the target and more.
Shooter variables - Can you properly adjust your scope/point of aim for the above variables. Do you have the ability to pull the trigger without affecting the shot. If you miss, can you compensate and take the second shot the same way?
Using my long range rig, I can hit 1 inch targets at 100 yards all day long. 1 foot plates on up to 400 yards all day long, given about half a minute between shots.
Give me a minute and I can transition from 0 on up to 400 yards. 400-700, I'll probably need a few minutes. 800-1000, I'll probably miss 2 shots before getting one on a still b-27 target (23x35). Then I'll miss every other round depending on how consistent the wind is. Most of my experience lies under 500 and I've only gone out to 1000.