Hmmm... Not sure where to start.

I'm looking for a scope for my 24" AR15.  It's supposedly a very accurate gun and I’d like the most accurate scope for it.  I was almost positive I wanted the Zeiss Conquest 6.5-20x.  However, I just found a great deal on a Bushnell 4200 8-32x and now I’m kind of rethinking myself.  The scope length and weight isn’t an issue because it is mostly a range gun.  The most important thing to me is the accuracy and consistency.  Here are my fears and doubts if someone could answer them:

1.      I’m kind of worried that adjusting the 4200 from 8-32 might change point of impact.  Which  
        is going to be more accurate and consistent while changing magnification?
2.      Which has the better clarity?  Is the 40mm vs. 50mm objective an issue?
3.      Does the 4200 have target knobs?
4.      What about warranties?  The 4200 I’m looking at is used.

The answers to these doubts as well as any other info that could help me make this decision would be greatly appreciated.

Thanks,
Clint

Yahoo! search is your friend...

Zeiss 6.5-20x50

Bushnell 4200 8-32x40

While both companies make good scopes, I think you will be better off with the Zeiss.  It has target knobs and side focus.  I tend to believe that glass has better clarity and the larger objective will make the target appear brighter.  Zeiss also has a transferable unlimited lifetime warranty.