I wanted to put an low power scope on my 20" flat top.  

  so I ordered a simmons 1.5x5x20 prodiamond an  Armalite one piece scope mount got both yesterday.

   I have 2 problems,The scope sets too low. My YHM BUIS won't fit under the scope and at the 1.5 thru 3 setting I can see the "ghost" of the front sight.    
   When I'm looking thru the scope I'm looking thru the front sight tower. Is this normal?  What can I do to get the scope high enough to  fit my buis  under the scope and get the sight tower out of view?

    I'm thinking about just going with an PRI extended riser and a set of warne rings.  But I don't know what  size of rings I'll need, high,ultra high?  
 
     Thanks very much for any and all advice and help.  Bill

The cheapest way would be to mount the Armalite mount onto a YHM rail extension. This will raise the scope by 1/2-inch. I have one, and it's a perfect fit onto my BM upper. The best part is, it only costs $35 (plus shipping) if you order directly from YHM.

ETA: Yes, it's normal for there to be a "ghost" image of the FSB when using a lower powered scope behind it. Past about 4x or so, the FSB disappears, due to the focal length of the scope seeing "through" it.