Crooked 6920...

[noops]

I've got a colt 6920 that I recently slapped a KAC RAS onto. Well, when I get the RAS's upper clamp around the gas tube and tightened down, the RAS is considerably misaligned, since the RAS is crooked as a politician and doesn't much line up with the receiver.

My question: I just did a carbine course with no problems, and I don't really care about it's crookedness from aesthetic standpoint. But is there any mechanical reason why I should get it straightened out?

[Buck]

I believe there is a USGI tool that is used to align the rail and the upper when the rail is being installed before it is locked in place...

B

[markm]

since the RAS is crooked as a politician and doesn't much line up with the receiver.


I'm not tracking on this....

The RAS has the clamp that straddles each side of the gas tube. The gas tube goes into the upper exactly in the middle. I don't see how it's mechanically possible for the RAS to be off at all.

Can you get a pic?

[Iraqgunz]

The only thing that I can think of is that the barrel nut was possibly overtightened and that has caused misalignment of the gas tube. Or the rail isn't sitting into the delta ring the way it is supposed to.

Do we know for sure it is a real KAC RAS? Anything made by man can be screwed up so it is entirely possible that the rail or something else is out of spec?

[noops]

It is definitely a standard OEM real KAC RAS.


The only thing that I can think of is that the barrel nut was possibly overtightened and that has caused misalignment of the gas tube

This is exactly what it appears to be. It does look like it was overtightened and went too far. I'll try to get pictures tonight.

If it's overtightened, does it matter? Does it really need to be straightened out?

Thanks

Noops

Edited to add: I will admit, this RAS has some miles on it, but I don't think it's bent anywhere, or especially at the upper clamp.

[scottryan]

I deal with this all the time. The barrel nut can still be aligned enough to fit a gas tube properly but when the RAS is installed, it can be pitched +/- a degree.

You have to reset the barrel nut and test fit the RAS as you go a little bit at a time to get the RAS square with the receiver.

You have to look down the receiver rail and onto the RAS to see if they line up which I assume you already did to find this misalignment.

[Robb Jensen]

Exactly.

I tiny amount of misalignment at the barrel nut gas tube notch gets worse the further out you go from the barrel nut ([I]meaning you'll see it more at the rail and even more if there's an attachment on the rail).

I've repaired many ARs with LaRue rails where the end-user installed it at home and can't figure out why the rail isn't lining up with the receiver.

With the LaRue rails sometimes you can loosen the two anti-rotational screws and the slip ring and re-align because there is a small amount of play laterally, just hold the rail whichever way it needs to go and then tighten the slip ring and the anti-rotational screws.