I don't know which is more sad the original post or the "tag".

Quoted: I WANT MY AR TO WORK WITH THE ELEVATION KNOB.WTF HOW DO YOU SIGHT IT IN AT 100 TO MAKE IST WORK...

You don't.  Assuming A2 sights, you sight it in at 50 yards, using the large aperture and the dial set at 8/3.  You can also do this using the small aperture, but then you have to reset your elevation knob so that it bottoms out 2 clicks below the 8/3 setting, to account for the difference in height between the apertures.  If zeroing with the small aperture, you click down to 8/3 -2 clicks.  (NOTE: if using detachable carry handle sights, you must click FOUR clicks down, as they have finer threads and twice the number of clicks per MOA of adjustment).  When you are done, flip back to the large aperture and make sure the wheel is set back to 8/3 (or 6/3 for detachable handles).

Once you are zeroed, you use the large aperture 99% of the time, as it will be very close at all ranges between 0-250m or so.  That's because, with this zero, you will be within 2 inches of the line of sight from 0-220m.  The bullet will start out about 2" below the line of sight (that's about how much higher the front sight is over the center of the bore), and will angle up, crossing at 50 yards and continuing to rise until it peaks at about 2 high at around 120 yards or so, then begins to fall, crossing the line of sight again at 200m/220 yards.  Before someone asks, the bullet rises because the barrel is slightly angled up when the sights are level (i.e., the rear sight is higher than the front sight, causing the rear of the rifle to be lower when the sights are level).

If shooting at 300m, simply flip to the small aperture.  Beyond 300m, you start adjusting the elevation wheel; 4 for 400m, 5 for 500m, and so on.  Obviously, in real life, you will almost NEVER move your elevation wheel, because you will rarely shoot further than 250m.

A2 sights adjust to 800m (assuming M855 ammo and a 20" barrel), and detachable carry handles adjust to 600m, which is the halfway point on an A2 800m sight.  That's why a detachable handle's sight has twice the thread pitch and requires twice as many clicks for the same elevation.  The screw that allows 800m of elevation on the A2 sights would stick out .5" from the bottom of a detachable carry handle, so a shorter screw is used.

-Troy

Quoted:

Quoted: You don't.

Quoted: You could've said that then.

A simple search would have saved him having to ask.

Yes, I'm a Mod what about it?

Quoted: Is it too much too answer questions?

Yep.

Never do for someone what they can easily do for themselves.

it breeds laziness