I've got an SWFA 1-4x24 scope on the way to go on my Ruger AR-556 so I've started shopping for scope mounts. I don't want to spend more than $100 on a mount, so I've been looking at the Leupold and Burris mounts, among others. In my shopping I ran across the Primary Arms extended scope mount; at $60 it looks like a good deal. Anyone have one? If so, how do you like it?