Hey there, im new on here and recently acquired an AR for a nice price.  Its a A1 1/2, carry handle A1 with the deflector behind the ejector port and A1 BUIS.
I feel that my eye sight at 49 has let me down for any accrurate shooting so im looking at a scope to mount on top of the handle.  I installed a Z rail
on the handle and have come across a Barska 3-9x42 GenII Sniper scope under consideration.  
My thoughts are this would be for 100+ target plinking and what i dont know is what mounting rings i would need height wise.  Im thinking the "low" mounts
but not sure since i would like to still use the BUIS for close in and back up.  These scopes are currently on sale for 50%-60% off depending on where you shop
so i think its a good buy for just starting out and not going for top of the line stuff........yet.  That will depend on how much i start out shooting and if the cost of ammo
comes down later on.
Thanks and look forward to ideas and input.
Sam

Don't buy Barska anything.  Junk, save your $$ and buy something else.

Carry handle mounts, IME, result in a poor cheek weld and/or incorrect eye relief.

If you want to mount optics, swap out the upper.  A flattop receiver is ~$100.

Lowest rings you can find and put something other than a Barska in them.  I would recommend a Primary Arms red dot on the front (low) portion of your rail in order to co-witness your A1 sights and keep proper cheek weld.  Otherwise, get a riser/pad for your stock.

Look around for decent scopes and you'll be much happier.  I'd get something like this for lower cost quality:
Don't buy Chinese crap for distance shooting

Avoid among others: Barska, BSA, Leapers, NCStar, Tasco, UTG, Bushnell Banner

Is there anyone that can give insight to the new Gen2 scope?
With the 2 replies so far, i am looking at other scopes but still wanting to stay in the sub $100 range, no more than $125 for a knock around, starter type.  
Reason i asked about the mounting rings is i know it would be high and i dont have the money to buy both a new upper and a scope.
The Gen2 scope list for around $250 and i guess they are trying to promote it for $120.  

if there is another scope equal as to features, i think it would be much more, but with so many brands and features to choose from, not knowing much at this point
was ther reason to ask here before spending what money i do have.

So for the moment, still looking and trying to sort out what is availible.

The cheapest scope I STILL HAVE is a Vortex Crossfire that was such a good deal I had to give it a try. Great optic for the money. Do some more reading in the optics forum. Years ago I tried cheap stuff and found I was just throwing cash away in the end. I personally like the Bushnell Elite line of scopes but I've heard that the newer 3200s are being made in China now not Japan. I'll be the first to say it "Buy once cry once"

Edit; a scope on top of an A1 or A2 upper receiver is very hard to be consistent with, you really should mount a optic on a flat top upper.

Looks like i will put a hold on a scope for the time being.  Most shops around here have NcStar, Aimpoint among others and i looked at a NcStar tactical with laser, 3-9x42 Mildot for 165.
So still looking and trying ot find local shops for that hands on look.
Thanks for the replies and info so i hope this might help others in the same boat as i am.
Sam

I went and bought  a flattop upper and will convert my A2.   This will allow a better mount for the scope.
Also what is a good rear site to attach and use with the standard height FSB.

Daniel Defense Fixed, LaRue Fixed, and Troy Folding are some of the most popular.  YHM if you're on a budget.  The Troys are available under a bunch of different labels including LWRC, BCM, and LaRue.  Lots of them pop up used on the EE.  

Just a heads up that you cannot use BUIS with a magnified scope unless you remove the scope.  If you're using a non-magnified optic like an Aimpoint or Eotech, you'll be OK.  

Check out LaRue SPR mounts for mounting your scope.