Jump to content
308AR.com Community
  • Visit Aero Precision
  • Visit Brownells
  • Visit EuroOptic
  • Visit Site
  • Visit Beachin Tactical
  • Visit Rainier Arms
  • Visit Ballistic Advantage
  • Visit Palmetto State Armory
  • Visit Cabelas
  • Visit Sportsmans Guide

Handguard nut alignment


Recommended Posts

Hey, I'm building my first 6.5 cm ar. Everything is in except my barrel. I was dry fitting my 17in utg pro handguard and based on the instructions I need to add the provided shims to get the holes aligned. Even with all 4 shims I have not achieved alignment. Anyone familiar with this? Thanks in advance.

Link to comment
Share on other sites

1 hour ago, NcPC said:

It's a free float and screws to the upper

That doesn't mean a single thing, until your barrel comes in, and you put the flange on that barrel right up against the upper, then screw that barrel nut down over the flange on that barrel. 

You are trying to figure this all out, without accounting for how thick that flange is, on your barrel, that you don't have yet.

Edited by 98Z5V
Link to comment
Share on other sites

On 4/13/2020 at 4:05 AM, NcPC said:

Thanks for the feedback I did not know the barrel flange affected the depth of the barrel nut. Got about a week or two before my barrel gets here. I will update you guys and post the build if I'm able to complete it then.

It most definitely does, and you have to account for it - there's nothing that you can try to calculate, before you actually receive your own barrel, and install it.  You can't figure out the timing of the barrel nut unless the barrel is IN the upper receiver.  Check out the flange that I'm talking about:


It's not minor, either - and it's not "standard" on a .308AR.  Nobody can give you a number on that thickness, and even if you had it, you can't calculate it to try to time a barrel nut beforehand.  Look at this thing:


That flange is what the barrel nut locks to your upper receiver. 

Link to comment
Share on other sites

10 hours ago, NcPC said:

Didn't even dawn on me the BARREL nut actually was for the barrel 

😁  So once you get your barrel put some anti-seize (very little) on the threads of the upper. Torque to 35lbs in 20-25-30-35lb stages. Each time unscrewing the barrel nut with a breaker bar (not your torque wrench) before going to the next stage. This seats the threads. Torque to 35lbs and inspect gas tube alignment. I don't know anything about your guard but here's where I would start following the guards instructions and using the shims to get things lined up. You'll have to continue to torque upwards until everything lines up. It should line up at some point between 35 and 80-90. I hear you can go higher but I'd be scared for my upper. Others will chime in to help if I made any omissions.

Link to comment
Share on other sites

5 hours ago, PaddyMac said:

It should line up at some point between 35 and 80-90.

30lb/ft to 80lb/ft is the M16/M4 Spec.  The same should follow on the .308ARs - if we had a spec to follow.  Unless your handguard manufacturer specifically states something direct, like 50lb/ft.  30~80 will get it done, lined up, and works on every small-frame AR (M16 and M4) out there in military service.

Edited by 98Z5V
Link to comment
Share on other sites

  • 3 weeks later...

Hey everyone I finally received my barrel after some shipping hang ups. Worth the wait! Here is the finished build with the exception of after market trigger that i recently purchased on sale at midway... can't get photo to upload.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...