Have a bushmaster vmatch 20" and a Saiga ak 16"
Both are zeroed at 50 yards. The vmatch is dead on at 200 yards, the saiga is about 6 inches high at 200 yards. Why the difference? Both are shooting Fed AE 55gr. Thanks

ARs are just better! ha ha

Did you slide the elevation adjustment up to 200 on the AK rear sight?

They are both scoped

On the rifles, the height of the scopes over the bore line is different and the speed of the ammo is different threw the two rifles.

To see this, draw a line that slightly curves downward (bullet path) then draw a second straight line (scope view) above the curved line that intersects the bottom curved line at a given point (100 yards).  The higher the second straight line is over the bottom curved line will dictate (make the points longer apart) where the lines will re-intersect at a second point threw the lines.  Also to point out, the AK barrel is shorter, which means that the bullet is traveling slower than the 20” barrel, which makes the bullet flight path of the AK more curved due to the bullet travel less distance during it gravity drop (bottom curved line).