Cobra 246 More info is needed. Are you going to hunt game at 1000 yards or are you just wanting to be able to hit a target at that range?
A lot of the hunting bullets about 600 yards change the meplat (nose) shape and start behaving erratically. You are probably going to have to search for a hollow point bullet to get paste the in flight deformation.
You are going to have to start reloading to achieve the maximum capability of your rifle. As well you will probably need to get the action bedded.
As a general rule light hunting rifles do not do well at 1000 yards if continuous shots are fired and they heat up but then again I have seen light barrel rifles do well for 20+ shots at long range but they are rare.
To achieve the smallest dispersion (most call this accuracy) your ammo needs to be precision loaded and chronographed and you are looking for a standard deviation as small as possible.
For instance if you have a 30 cal rifle and are loading 180 grain bullets and your loads give you an extreme spread of 100 fps, you will deliver vertical dispersion of about 40" at 1000 yards. Logically if your ammo has a 50fps you are looking at 20" vertical dispersion.
Now lets say you are shooting at the conventional 1000 yard target the 10 ring is 20" diameter and if you have absolutely no aiming error, and can dope the wind you can shoot all 10s but not likely.
Thus you need a extreme velocity spread of 25 fps which theoretically gives you a 10" group which is the size of the X ring.
I would not recommend a scope with over 10X for such shooting because the higher your power the more mirage you are going to pick up and seeing through mirage is a trick as it tends to refract light and the target is not where you think it is.
OK lets say you have a rifle that will print 1" or less at 100 yards and your ammo has an extreme spread of 25 fps that is only a start but a good one.
What you will next need is a very good range finder because at ranges beyond 600 yards the drop every 100 yards can be from 10 to 15 inches thus you need to know the exact range and have a confirmed zero.
Next the wind effect on your bullet can be enormous. For instance I have shot in winds where there was so much windage cranked on my sights, had the wind stopped I would have hit the target 8 feet right. I have shot with guys who have shot service rifle and they literally had to aim at the target next to theirs to get the bullet to hit the intended target.
I have a target board 4' wide and 8' high. I start with a 300 yard zero and place a target at the top of the 8' board. Move back to 400 and shoot three shots, then to 500, 600 and so on you will give get a idea quickly of how a increase in range will affect you bullet. Measure the distance below center of target aimed at to each bullet hole and record the drop in inches and average the drop.
Next make up a chart of the bullet drops by yard line. It will be a very educational experience for you.
