bought my first ar, a colt, lt. weight with fixed handle, love the weight and accuracy for the 100-200 yard plinking I do, the problem is the scope set up, bought an NCStar 3-9x42 and love it, great for a beginner like me but the eye relief is driving me nuts, best I can tell I need a scope mount that allows a longer scope to extend about 3" beyond the end of the charging handle towards my face since most scopes have a 2" eye relief, and info on any set up would be appreciated or should I:
1. replace the reciever w/a flat top, anybody know what would be a good brand would be and how much... can I use the same bolt?
2. sell the entire upper on ebay and get a new one with flat top and removable carry handle... how much should I pay, whats a good brand and what is  my colt upper worth?

Sorry for all the ?'s but I figure you all would know- Thanks!

Before the drastic changes to the rifle, have you considered a different scope?
None of the changes you mention are cheap, and a different scope may be the best/most cost efficient fix-- especially considering the cost of NCStar scopes.

Also you may want to try a different head position: either closer to the "nose on the charging handle" for all-around shooting-- irons or scope (and that may help shorten the required eye relief for the scope as well) OR a cheek rest.  A scope mounted above the handle for hunched-over benchrested shooting may feel to far forward (your case) for off-hand if your head position is too far away from the rear sight while standing.

My buddy requires an incrediably long length of pull for his stocks and when he shoots my AR's off-hand his head is way back on the stock for an eye releif problem similar to what you describe.

All of the above are much cheaper than swapping receivers, etc. and probably closer to the root of your situation.

Its just my opinion.
Cheers, Otto

Bluecoat, for what it's worth, I generally try to get the eye of my scopes in line with the charging handle, or forward of it.  Eye relief in scopes varies, but I try to get it so that my nose will be as close to the charging handle when I sight scoped rifle, as it is when I'm looking through the iron sights...I'm trying to achieve "muscle memory", or the same feeling no matter which one I'm shooting.  

The problem for me is the opposite of what you're having...I'd like to mount some of mine further forward, not back.  I don't think any of my scopes have optimal eye relief at only 2"...it's much closer to 3 to 4", or at least it feels that way.  

Since this is your first AR, you might be a little reluctant to get your face and nose in there real tight...but after a while, it will feel natural to you..and that will more than likely solve your eye relief problems.  

You might shoot it a bit with just the iron sights...on my 20" HBAR, which barely kicks at all, I put my nose ON the charging handle.  On the 16" guns, that kick a little more, I back off about an inch...but no more than that.  

Check your position when you shoot it with the iron sights...if you're any further back than 2" from the charging handle, you might try moving up some, and see how you do.  

I wouldn't really worry about swapping any thing out right now...you say in the first sentence you love the rifle, so don't be in a hurry to change it...work with it a little, and see how it does.  Also, see if anyone you know has a spare scope you can borrow, and see if that improves it any.  

Scopes mounted on the carry handle DO cause some problems...without knowing the overall length of the one you have, it's probably around 11" or so...that can make for awkward sighting on the carry handle.  A shorter scope that allows you to move forward with your face on the stock may be the answer.