308 sight in help.

Projectile weight and velocity required to form drop chart.

With a 200y zero I'm 85" low at 600.

Yup, what bullet, what ACTUAL velocity?

With that much variation you need to be using a scope with either multiple aiming points or one where you twist dials. For pure target shooting dials are more accurate, but take longer to dial in. I like long range dots better for hunting. Not as precise, but faster to use.

You zero at 100, sometimes 200. On a scope with multiple aiming points you'll have hash marks or dots on the vertical post that should be pretty close at 200, 300, 400, 500 etc. It won't be perfect, but close enough to hit big game animals at those ranges with most cartridges. If you need more precision than that it isn't hard to figure it out with practice exactly how much hold over/under you need. You might still be hitting 4" low at 400 yards for example, but it is a lot easier to compensate for 4" of hold over than 4' with a conventional scope.

If you twist dials you need to enter the bullets muzzle velocity, BC, and other data into a ballistics calculator. There are several options online. I use this.
https://www.hornady.com/team-hornady/ballistic-calculators/#!/

You can then calculate drops at ranges out to 2000 yards with most programs. It will tell you how much you need to adjust the scope for any range in 25 yard increments. You then zero at 100 and use the technology to account for hold over.

If shooting beyond 300 yards is going to be rare you can do the same thing with a conventional scope. There isn't enough drop at 300 and under to worry about, it is easily accounted for. You still zero at 100 and turn the adjustment dials on the scope to account for longer ranges. You just have to remove the scope cap whereas the others are made with adjustable turrets and are a little easier to use.

Jeff Burgess said:

Im suppose to pick up a Windham Weapondry AR10 this week and been wondering how to sight it in. This will only be a range gun.
The CMP ranges are at 100-200-300 and 600 yards. While I can sight in at 100 and adjust for 2-300 yards as I go but what about the 600?
How much higher would I need to aim at 300 to hit the 600. Once it’s on the target I can adjust it from there.

Click to expand...

Is this going to be specifically for a CMP competition class? If so, what events you plan to shoot will shed a lot of light on what you will need for optics, loads, and zeros. The .308/168BTHP is remarkably similar to the 5.56 75 or 77 magazine fed load in terms of come ups, at least close enough to get you on paper and walk in sighters. If you do get optics or irons with repeatable elevation adjustment, I can share my zeros. I have both iron and optic zeros, but you'd have to convert my optics from Mils to MOA.

Pulled these off another thread on another forum with a quick search. I'd have to check my books to be sure, but they sound "ballpark"
federal match 308 HP BT
yards MOA 1/4 clicks
100-200, 1.5, 6
200-300, 2.5, 10
300-400, 3.0, 12
400-500, 3.5, 14
500-600, 4.25, 1
600-700, 5.0, 20

Sight in for 200yds
For 300, come up 2moa. (8 clicks for most scopes)
For 300 to 600, come up 10 MOA, or 40 clicks

Be sure to mark your zero elevation setting. I like white paint. Use yellow for the 300, red or orange for 600.
Green or blue for 100yds.

100yds is DOWN 1 MOA from 200yd setting. 4-clicks Down.
(For 1/4moa adjustments, double if 1/8moa, half if 1/2moa.
Works for .308, .30/06, and 5.56 with 62-80gr bullets...
Who’d thunk?!

I highly recommend the Strelok app if you have a smartphone for figuring out these kinds of ballistics. It has a little bit of a learning curve but once you get it down it's great for getting a rough idea of adjustment clicks, hold over/under, etc..

It has quite a few factory loads programmed in for alot of different calibers, and you can input your own variables if you reload or get more accurate numbers via chronographing factory loads with your particular rifle, etc..

Just as an example, here's a table and "BDC calculation" I made on the fly for my Savage 10 FCP in .308. I used the factory specs in the program for Winchester PowerPoint 150gr and a 50 yard zero.