I have a del-ton assembled AR-15 (love it by the way) and since it's a flat top, I bought a Weaver brand carry handle/rear sight.  Now, I noticed that I had to move the windage far to the right to get the shots more or less central to the target.

Now, I did a basic check by placing the rifle upside down on my glass computer desk with the sight attached and it does wobble.  I'd say maybe .300" or so.

When I take the handle off and try the rifle again, it's perfect.  When I lay the handle by itself and test it, it does wobble.  The guides or long "ears" aren't parallel.  Is this a problem enough to take the thing back and get a refund?  (i'll probably just get store credit and buy ammo.)

Anyway, maybe someone more experienced can chime in, I could really use the advice.  I'm going for a BUIS either way but I don't want to have wasted my 90 bucks on a non-perfect carry handle/sight.  

The Weavers are known to have some problems.

It is normal for a rear sight to be twisted slightly counter clockwise because of a spring and bearing in the left side of the sight.  But the handle shouldn't wobble.

The handle definitely wobbles.  Maybe I should take it back then...

Delton or no, I think you need to at least consider the possibility the FSB isn't square to the upper ... i.e., the barrel is a little out of index or the FSB isn't properly pinned.

If possible, get another carry handle (borrow one or exchange yours for another one) and try the rifle again for accuracy. If the second carry handle still needs to be ratcheted over the far right, the FSB is probably crooked.

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I don't know anyone with an AR so I can't really get another carry handle to try unless, like you said, I exchange it for another.  Like I said, I did put the rifle on a flat surface without the handle in place and it was fine.  I made sure the charging handle wasn't in to make sure the flat top was in fact, flat.

I'm probably going to take this back tomorrow afternoon after work.  Any reason I shouldn't, please let me know.

how many clicks do you have to adjust the rear windage for it to zero?

I'd say about 18 to 20.  It's probably within spec for the military.

Having to put in excessive clicks fro zeroing is USUALLY because the FSB is canted (either installed wrong, or the barrel has slipped a bit. 18-20 clicks is JUST within the spec.