Let's look at an example of factory ammunition out of a 24" barrel 308.
Hornady Manufacturing Company :: Ammunition :: Rifle :: Choose by Caliber :: 308 Win :: 308 Win 165 GR InterBond® Superformance®
Let's use a reasonable altitude of 8000 feet, temp 50 degrees for elk terrain.
Trajectory
Input Data
Ballistic Coefficient: 0.447 G1 Caliber: 0.308 in
Bullet Weight: 200.0 gr
Muzzle Velocity: 2840.0 ft/s Distance to Chronograph: 10.0 ft
Sight Height: 2.10 in Sight Offset: 0.00 in
Zero Height: 0.00 in Zero Offset: 0.00 in
Windage: 0.000 mil Elevation: 0.000 mil
Line Of Sight Angle: 0.0 deg Cant Angle: 0.0 deg
Wind Speed: 10.0 mph Wind Angle: 90.0 deg
Target Speed: 0.0 mph Target Angle: 90.0 deg
Target Height: 12.0 in
Temperature: 50.0 °F Pressure: 29.92 in Hg
Humidity: 0.0 % Altitude: 8000.0 ft
Vital Zone Radius: 5.0 in
Std. Atmosphere at Altitude: No Pressure is Corrected: Yes
Zero at Max. Point Blank Range: No Target Relative Drops: Yes
Mark Sound Barrier Crossing: No Include Extra Rows: No
Column 1 Units: 1.00 in Column 2 Units: 1.00 mil
Round Output to Whole Numbers: No
Output Data
Elevation: 1.203 mil Windage: 0.000 mil
Atmospheric Density: 0.05780 lb/ft³ Speed of Sound: 1106.7 ft/s
Maximum PBR: 358 yd Maximum PBR Zero: 305 yd
Range of Maximum Height: 170 yd Energy at Maximum PBR: 2357.8 ft•lbs
Sectional Density: 0.301 lb/in²
Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(yd) (in) (mil) (in) (mil) (ft/s) (none) (ft•lbs) (s) (in) (mil)
0 -2.1 *** 0.0 *** 2845.4 2.571 3594.8 0.000 0.0 ***
50 -0.5 -0.3 0.1 0.1 2765.6 2.499 3396.2 0.053 0.0 0.0
100 -0.0 -0.0 0.5 0.1 2687.4 2.428 3206.7 0.108 0.0 0.0
150 -0.7 -0.1 1.2 0.2 2610.5 2.359 3025.8 0.165 0.0 0.0
200 -2.7 -0.4 2.2 0.3 2534.9 2.290 2853.2 0.223 0.0 0.0
250 -6.1 -0.7 3.5 0.4 2460.6 2.223 2688.4 0.283 0.0 0.0
300 -10.9 -1.0 5.1 0.5 2387.6 2.157 2531.2 0.345 0.0 0.0
350 -17.2 -1.4 7.1 0.6 2315.8 2.092 2381.2 0.409 0.0 0.0
400 -25.1 -1.7 9.4 0.7 2245.2 2.029 2238.2 0.475 0.0 0.0
450 -34.7 -2.1 12.0 0.7 2175.8 1.966 2102.0 0.543 0.0 0.0
500 -46.2 -2.6 15.1 0.8 2107.5 1.904 1972.2 0.613 0.0 0.0
550 -59.7 -3.0 18.5 0.9 2040.6 1.844 1848.8 0.685 0.0 0.0
600 -75.2 -3.5 22.4 1.0 1974.8 1.784 1731.6 0.760 0.0 0.0
650 -93.0 -4.0 26.7 1.1 1910.4 1.726 1620.5 0.837 0.0 0.0
700 -113.1 -4.5 31.5 1.3 1847.3 1.669 1515.2 0.917 0.0 0.0
750 -135.8 -5.0 36.8 1.4 1785.6 1.613 1415.7 1.000 0.0 0.0
800 -161.2 -5.6 42.5 1.5 1725.4 1.559 1321.9 1.085 0.0 0.0
850 -189.6 -6.2 48.8 1.6 1666.8 1.506 1233.5 1.174 0.0 0.0
900 -221.0 -6.8 55.7 1.7 1609.7 1.455 1150.5 1.265 0.0 0.0
950 -255.8 -7.5 63.1 1.8 1554.4 1.405 1072.8 1.360 0.0 0.0
1000 -294.3 -8.2 71.1 2.0 1501.0 1.356 1000.3 1.458 0.0 0.0
21/02/12 22:48, JBM/jbmtraj-5.1.cgi
Over 1500 ft*lbs at 700 yards and over 1800 fps with factory ammo. It's not 800 yards for the 1500 energy stipulation, but close (1321). Plus it is a whole lot cheaper and easier to practice with than the magnums. If you reload you may be able to do a little better with a 200 SGK, runs at 2500+ fps out of my 20" TRG with MR-2000, probably get around 2600fps out of a 24" barrel.
but i dont have the experience to know for sure about all the technical specs on long range sniping
You know how you get experience? With lots of practice in a variety of conditions. Don't expect the better ballistics of a 7mm Mag (although good factory loads with high BC bullets may be hard to come by) to compensate for a lack of experience. Yes, you have to have enough energy for a reasonable expectation of bullet performance on game. A high BC does help in difficult wind conditions. But shot placement from a hunter that knows his rifle/ammo inside and out is likely to be much better than one that shoots the magnum every now and then.
I would hold off on rigid distance requirements until you get some experience. You will quickly see that the conditions and your available shooting position will likely alter your accurate FIRST round hit range.