I've mounted an Aimpoint Comp M2 on my M4. The gun's sighted in at 100yds.  How do I do a 200 yd holdover shot with a red dot?  The problem seems to be that since the dot can be anywhere in the scope's field of view, it doesn't seem logical that it could be done easily.  

I don't have a ballistic table in front of me and I don't know precisely what ammo you are using but I wouldn't expect more than about a 2 inch change of POI.

Why didnt you just have it zeroed at 50 yards like you are supposed to?  Then it would be pretty much dead on at 200 yards.  If thats not an option then just aim at the bottom edge of the dot for an aiming point.  Bullets should fall just under the bottom edge of the dot at 200 yards.  I still say zero at 50 yards like it was intended.

Well, I just gave the Aimpoint instruction manual ANOTHER look-over and I don't see where it specifies a 50yd zero.  

The suggestion to use the bottom edge of the dot as an aiming point is a good one.  I'll try it.  Thanks.

If you zero at 50 yards where all M16 platform weapons are supposed to be zeroed you have a zero of 50 and also 200 or 250 yards depending on ammo and barrel length.  This is with irons sights or Aimpoints.  Your only going to be an inch or two high at 100 yards as the bullets tracks well enough to hit INSIDE the size of the dot from just inside 50 yards all the way to 250 yards or so.  About 99% of the people on this board have the Aimpoint zeroed this way.  Then the bottom of the dot could be used for aiming at 300 yards instead of 200 yards.  Just my suggestion as it allows you to just put the dot on the target and pull the trigger and not worry about hold over.