I sighted in a new AR yesterday, using a carry handle for the rear sight.  The distance was at 25 yards and the rear sight was turned down as far as it would go (6/3)  When I got the rifle zeroed in, I noticed the round base of the front sight post sits about one "click" above the part that reads "<-- UP".  On my other AR's I noticed the round base of the front sight post sits either below or flush to the "<-- UP"   Not having ever installed or taken apart a front site, about how many "clicks" above the "<-- UP" will I have before the sight pops out?  From where my sight sits now, do I need to worry about it or no?  Thanks!  

About 3/8 of an inch which is a whole bunch of clicks.

No, don't worry about it as it's designed to adjust the elevation.

Improved Battlesight Zero @:

communities.msn.com/TheMarylandAR15ShootersSite/zeroingmethods.msnw

This is a much better zero than any you'll find in a manual.