Consequence of not going to full torque for an AR barrel nut.

[jlow]

I now understand the method and how it is best to go high in terms of torque to line up the hole for the gas tube hole.

My question is if you use the hole resultant from the lower (30 foot pound) instead of the high (60-90 foot pound) torque, is there a consequence on precision/accuracy?

I put a gun together this week with the low torque method and is finding some wild flyers (2” groups) using a Kreiger 1:7.7 20” 223 barrel and so was wondering if this was the cause of the problem. After doing the multiple torque, I now got the hole to line up using the high torque. Hoping it would solve my problem but wondering if that was the cause?

 

[chromatica]

Shims are available that allow you to align the gas port holes at the torque setting of your choosing. I know I have seen these at either Midway or Brownell's, but I can't easily find them. Quite a few vendors on Amazon offer kits. Here's one:

http://www.amazon.com/ar15-freefloat-Barrel-Washers-Shims/dp/B00JS6JOT0/ref=sr_1_6?ie=UTF8&qid=1402109810&sr=8-6&keywords=ar+barrels

You can also lap the front face of your receiver to get the holes to line up using the following tool:

http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/receiver-tools/ar-15-m16-upper-receiver-lapping-tool-prod20220.aspx

 

[nicholst55]

What you describe is often caused by a too-loose barrel nut. While max torque isn't necessarily required, you don't want the nut too loose!

 

[msalm]

I would face the receiver to ensure it's perpendicular and even, that usually is only a thou or two and it will also put you in the middle ground of torque values for the 'next notch' that seems just a little too much. Also, consider a sleeve of red locktight around the barrel extension. It will fill any gaps and take out any play. To remove in the future it just takes a little heat and the barrel will pop right out. (don't get any loctite on the barrel nut threads, in fact those should have a good quality moly grease on them).