I have used the search engine and read several posts on AR regarding these sights. I intend to experiment with one, first on a lever gun, and, assuming success, later on bigger bores, and I thought I was ready to make the jump until I read the specs. On the Trijicon web page, which is the only place I found specs, it says "parralax free at 40 yards" or something very similar to that. In general I know what Parralax is, but I don't understand what this spec means in terms of use of the sight. My thinking was that these sights (with 3.5 min. dot) are effective at ranges from 0 to 200 yards, is this true? I would appreciate anyone sharing their experience.

I have shot a Docter Optic quite a bit at 300 yards and a fair amount at 400 and 500 with no problems.

Have you considered the EOTechs?

The EOTech is essentially parallax free to infinity.

I have two and really like them.

The EOTech is a great sight for a combat AR, etc.

I have shot a "few" rounds through one.

My favorite is the one that takes the same 123 batteries as the Surefire lights...

However on a hunting gun it is WAY bigger, and heavier, than necessary.

The new ones are about 11 oz and have a single battery perpendicular to the bore.

Much smaller footprint that the older AA version

No heavier than a scope.

http://www.eotech-inc.com/product.php?id=38&cat=4

Guys,
Thanks for taking time to reply. Basically 450's response answers my question. Duckear, one of the attractive things about the Docter sight is that it is small and light, less than one ounce if the spec sheet is to be believed. It strikes me as an upgrade to irons, easier to use for older eyes. My son has used the the EOTech (in Iraq) and liked it well enough to put one on his personal AR, so I am sure it is a good unit, just not what I had in mind for this experiment.
Thank you both for your help.