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View Full Version : AR15 zero irons first then red dot?


breakingcontact
January 21, 2013, 02:02 PM
I'm not a newbie with AR15's at all, but I am with optics on them.

How should a guy sight in an AR15 with backup sights and a red dot?

This is a Vortex Strikefire with the tall mount. Also, should the red dot just sit on top of the front sight if the irons are sighted properly? Should you be able to look through the backup sight and see the red dot right in the middle on top of the front sight post?

If this has been covered in detail elsewhere here, please redirect me.

Thanks!

hulley
January 21, 2013, 02:14 PM
I like to zero the red dot first and then adjust the irons to line up with the red dot, then shoot the irons to confirm. I just did this to another AR over the weekend.

hulley
January 21, 2013, 02:17 PM
Sorry I forgot to mention. I like a six o'clock hold on irons so therefore my dor will sit on top of the front post. I choose a six o'clock hold because the front post is black and often covers the target. I do a dead-on hold with a red-dot.

I dont think there is a specific way as long as the end result is the same.

DPris
January 21, 2013, 02:56 PM
Irons will not always co-witness with an optic.
You just have to try out your own combination & see if they're compatible.

I zero my irons two inches high at 100 yards, and then mount the optic & zero it.
Denis

breakingcontact
January 21, 2013, 02:58 PM
So the red dot won't always be centered (left to right) on top of the front sight post?

hulley
January 21, 2013, 03:29 PM
Irons will not always co-witness with an optic.
You just have to try out your own combination & see if they're compatible.



100% Correct. I failed to mention that the red-dots I have used were "absolute co-witness" and they worked out fine. Some RDs are "lower 1/3 witness" and some may have varying mount heights.

hulley
January 21, 2013, 03:30 PM
So the red dot won't always be centered (left to right) on top of the front sight post?


I'd think it would be more of an elevation difference.

DPris
January 21, 2013, 05:15 PM
It is an elevation difference.
Not all optic sights ride at the same height and not all are built to co-witness.
My ACOG, for instance, rides too high for irons.
Denis

AK103K
January 21, 2013, 10:18 PM
I prefer to zero the irons first. Then I dial the dot onto the top of the post, splitting the dot (half on top, half below). Then (with my AR's), I lower the BUIS and confirm the dots zero and fine tune it. When Im done, I bring the irons back up and check to see if they have changed, which they usually dont to much.

I have Ak's with Aimpoints on an Ultimak rail, and they are a lower 1/3 cowitness. Mr AR's are a center cowitness. With either, when I have my head down on the stock for shooting irons, the tip of the front sight pretty much splits the dot.