I just built my first AR15 using subassemblies which I bought at a local gun show.  DPMS lower, Wilson Arms upper half, Rock River buttstock.  The problem is with the Detachable Carry Handle.  It seems to be made for a narrower rail than my A3 flat top has.  I can mount it, but it doesn't center on the rail and I have to adjust windage way off to the left to zero the sights.  All input welcome.

Thanks,

Are you sure the handle isn't centered?  This is most often seen when the barrel isn't indexed properly, it twists as the barrel nut tightens down, causing the front sight base to be canted slightly (built in windage).

If it is the front sight post slightly canted, it is an easy fix and is covered in one of Tweaks FAQ's in troubleshooting.

I may have a slight cant on the front sight.  I'll read the FAQ and see.  I'm sure the handle isn't right though.

Are you also concerned about the slight twist in the rear sight, and it being spring loaded to one side?  If that is what you are referring to, it is supposed to be that way.  

The windage not being centered for zero is not that unusual, as long as you have some adjustment still available, it will work OK.  It just doesn't look right. I have one that is that way somewhat, but it shoots so well, I hate to mess with it.