Someone correct me if I'm wrong, but at 25 yards, the impact of your bullet should be low...1.2" lower than the target.
groups.msn.com/TheMarylandAR15ShootersSite/zerotrajectories.msnwCheck that out. Basically, if you want a flat shooting zero out to 220 yards, use the IBZ, which means zeroing at 50 yards. At distances shorter than 50yrds, you should be a little low. At all ranges between point blank and 220 yards, you should be within 2" or so of point of aim.
Someone correct me if I'm wrong, cause if I am, I'd have to go back to the range and rezero my rifle..
-Jim
-BTW - What BUIS are you using? If Arms #40, I think you need one of those taller front site posts, unless your upper is Colt (which comes w/it). I had one installed on my Bushie, and it matches up just right with my #40.
This could explain your problem..if you are shooting high at 25 yards, you need to raise your front site post. If you're unable to raise it high enough to zero correctly, then you should get the taller front site post. It's a pretty inexpensive item.