While I aim through my ACOG replica (it actually magnifies), there is a fisheye effect. I don't know how or why it is doing this, but I've completely disassembled the scope, and cleaned both lenses very well. I have also tried flipping the rear lens to no avail.
Could it be that this is occuring because it is just a replica? Or is there a logical explanation to this beyond the quality of the replica?