I recently had the opportunity to try out the Diamondhead Sight from Mirrorsight.com. I met the owner/developer, Dan Ballard, at the TTPOA show in April.
The Diamondhead Sight is a Troy Industries Flip Up rear Sight with a diamond shaped small and large aperture instead of the usual round aperture. Dan told me he has the apertures machined from the exact same materials Troy uses for their apertures and then Troy assembles the aperture into their sight.
Dan explained to me the sight was developed using right angles to form a diamond to help draw your vision quicker to the center of the aperture and to help provide reference points to allow your eye to put the front sight in the center quicker this is due to the fact the diamond shape and posts help to give the sight a simulated crosshair effect. Dan also stated he tried out many different shapes and ideas before coming to the conclusion the diamond shape aperture was the best option
I will admit I was skeptical if the diamond shape would do what Dan claimed it would. Dan quickly jumped and asked if I would be interested in looking through the sight. I will admit I was surprised how quickly my eye centered up the front sight post. Dan also offered me the opportunity to try one of the sights out during a patrol rifle class I was scheduled to attend at the end of April.
Dan sent me out a T&E sight and I was able to get it mounted in time for the class. The first half of the class consisted of shooting with the iron sights and getting the rifles zeroed in. I was surprised that I was actually able to get tighter shot groups than I normally get with the round aperture. This may be due to the fact the diamond shape allowed me to put the tip of the front sight post in the same spot every time.
I have shot with the Diamondhead Sight a few times since then and I keep getting the same consistent results. Overall, I am impressed with the sight and feel that it is something that all shooters of AR type platforms should look into.
Here are some links to pics I took on my rifle:
For much better pictures of the sight and more information on the sight, go to http://www.mirrorsight.com