No, they are just like the standard rear sight (I believe it's 3 MOA of difference).

The way A2 sights are designed to work, the large aperture is used at ranges of 200m and less, and zeroed at 50m.  When shooting at 300m and beyond, you flip to the small aperture (no adjustment from your "large aperture/50m setting).  If shooting beyond 300m, only then do you use the elevation dial.

-Troy

That's the zero I use, and tracks with my first post.

In order to use the small aperture to zero using the IBZ, your rear sight needs to be set up to bottom out to clicks UNDER the 8/3 setting (or FOUR clicks if you're using a removable carry handle, which uses finer threads).  The link you posted should explain how to adjust them if your sights aren't already setup that way.

Then, to zero, you use the small aperture and set the elevation to 8/3 -2 (i.e., 2 clicks below the 8/3 setting) for A2 sights, and 8/3 -4 for detachable handle sights.  Then, fire at 50 yards and use the front sight to adjust elevation until you're zeroed.

Once that's done, click your elevation knob back up to 8/3.  The small aperture is zeroed for 300m (approximately, and this will also be ammo and barrel-length dependant), and the large aperture will be zeroed for out to 250 or so yards.

-Troy

With the elevation dial set at 8/3, the apertures ARE zeroed for different distances.  The large one is zeroed for 50 yards/200m yards (it will cross the line of sight at 50 yards on the way up, will be about 2" high at 100 yards, and will cross again at around 200m on the way down), and the small one will be zeroed for 300m.  That's why you have to lower the sight (by clicking the elevation knob down 2 clicks) for it to be zeroed for 50/200 yards.

Normally, a military rifle will rarely if ever have its elevation knob moved.  Virtually all shooting is done with the large aperture, and ranges rarely exceed 200m.  When longer range shots are needed, the shooter will flip the aperture, and if the range is known and beyond 300m, only then will the elevation knob be used.

With A1 sights, which have no elevation knob, the only way to change the elevation (aside from adjusting the front sight, which wouldn't be done in a fight) was to flip the sight.  One aperture was zeroed for 250m, and the other for 325m.  The 250m aperture was used 99% of the time, again because combat ranges rarely exceed 200m.

-Troy