I ordered an Aimtech carry handle mount from Natchez, because they were inexpensive and made in the USA.  The mount was advertized as a see-through mount, but it needs some modifications to actualy work that way.  The mount uses an allen bolt which is screwed through a tapped hole in the bottom of the mount block; a knurled nut threads onto that to keep the mount on the carry handle.

The head of the allen bolt is tall enough that it takes up about 1/3rd of the see-through channel!  It completely obscures the front signt on my rifle.

To fix this, I am going to use a Dremel tool to cut a wide V shaped groove in the head of the bolt.  

Otherwise, these are nice quality, made in the USA, and cheap, and I heartily recommend them.  If you want see through out of the box, go with the B-square!