FYI parallax and fisheye are two different things:

http://en.wikipedia.org/wiki/Parallax

http://en.wikipedia.org/wiki/Fisheye_lens

I got to shoot one of my friends 20" RRA M4 AR-15's sporting a Nikon 3-12x Model 8489 AR-15 scope and matching mount, and I was SOLD. I'm saving up for one, but I'm not sure if I want the 2-8x or 3-12x. -TomT