Sights acting weird.

**Clyde777** · 08-09-18, 18:38

I have a factory bcm upper and the aimpoint I have on it is zeroed I also have a pair of Daniel Defense back up irons and noticed to co witness them with the aimpoint the rear sight must be drifted almost all the way to the left. Is this normal or what could be wrong? Its the buis on the rail and the rail is centered. When I put the sights on another rail it centered fine. So I guess its just the rail?

**GH41** · 08-09-18, 19:31

I have ask a thousand times..... Why is co witness important????? If you see the irons when using the RDS you are not using the RDS correctly!

**Clyde777** · 08-09-18, 20:02

Its not that co witness is important but if the dot is zeroed its easy to zero your irons as well in case the optic goes down and vise versa. You take your optic off for whatever reason lose zero and line it back up with the irons and your zeroed again.

**T2C** · 08-09-18, 20:03

It's definitely a mechanical issue. You should not have to move the rear sight more than 3-5 clicks left or right to obtain correct windage. Have you tried using two levels to verify both the upper receiver and rail are on the same horizontal plane? Canting of a component will force you to adjust windage beyond what you find is an acceptable amount to zero.

I did not know that co-witness of iron sights and red dot sights is an issue. I have been using it and teaching it to students successfully for over 20 years. What is the issue?

**Mr. Goodtimes** · 08-09-18, 22:30

Originally Posted by Clyde777

Its not that co witness is important but if the dot is zeroed its easy to zero your irons as well in case the optic goes down and vise versa. You take your optic off for whatever reason lose zero and line it back up with the irons and your zeroed again.

That’s not how that works.

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**MegademiC** · 08-09-18, 23:13

Sight in irons
Install optic
Sight in optic
Shoot

**AKDoug** · 08-10-18, 00:34

Originally Posted by MegademiC

Sight in irons
Install optic
Sight in optic
Shoot

Exactly. My DDM4V7 requires the rear sight to be almost all the way to the left. It's just the way it is. My Aimpoint dot sits above the fixed DD front sight on my rifle, but I never notice it while I'm shooting.