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AR uppers

Squirrely

By Squirrely
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Squirrely Enthusiast

Squirrely

Posted
Posted

Anyone here build them. I have a question or two.

 

Mostly, I'm having trouble getting the barrel to seat flush with the upper receiver. What's happening is a slightly canted barrel. So to sight in you have to crank everything to the right.

 

Am I missing a trick here?

Squirrely Enthusiast

Squirrely

Posted
  • Author
Posted

After some research.

 

I guess I will need to take my upper apart and check for debris. Then when I reassemble, I torque and loosen the barrel nut a few times to help assure that all is seated correct. If I still have problems then something is out of spec.

 

Guess I'll find out in a week

FargoZ71 Enthusiast

FargoZ71

Posted
Posted

Ar15.com is much friendlier. Debris, grease, tq, re tq, ect.. last ditch effort.. check the chamber to make sure its straight with the barrel...

Squirrely Enthusiast

Squirrely

Posted
  • Author
Posted

I'll probable tear this down this weekend. What a bummer too, I had it all done up nice, lock tight, etc. But if it doesn't shoot straight then it's no good.

 

I found some info on the AR15 site. Looks like I made a rookie mistake.

  • 2 weeks later...
hollis092 Enthusiast

hollis092

Posted
Posted

I build AR's and perform service and upgrades. Let me know if you need some help - PM me.

 

What was your mistake?

 

When you installed the barrel, was the barrel tit and the groove in the upper aligned? Torque your barrel down enough?


I don't ever use locktite - general rule of thumb - things always need to be taken apart for some reason.

  • 2 weeks later...
  • 3 weeks later...
Squirrely Enthusiast

Squirrely

Posted
  • Author
Posted

All right.

 

Tore it down today and took serious time to reassemble. There were a couple things I noticed that I missed last time. These may seem like common sense but I just figured it out, or so I think

 

The barrel nut has indents in it for the set screw on the quad rail. Once I torqued the nut, loosened and re-torqued 5 or 6 times, I had to take great care in making sure these indents didn't twist the rail once installed with the set screw. Basically I had to thread the quad rail, install the set screw, and check if all was square. If it wasn't then I took the rail off and ever so slightly added a little more torque to the barrel nut until I got everything straight.

 

I think I had everything ever so slightly twisted, and when you add up the distance of the sight from center of the bore, that was probably enough to cant my sights.

 

Hopefully I got it this time.

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