Upper Receiver to Barrel Nut Thread Tightness - Does it matter at all?

[Leicafan1990]

Sometimes you get a barrel nut that has a pretty tight fit with the upper receiver threads (no play, you need to use a bit of force to thread the barrel nut all the way) and other times you get a barrel nut that threads on super easy and wiggles around on the receiver threads until it tightens up against the barrel extension lip.

Does the tightness of the thread fit between the upper receiver and barrel nut matter at all if you are trying to squeeze the most accuracy out of your AR?

I’m curious if barrel nut with loose threads (but is properly torqued) is more likely to cause rail deflection or barrel harmonics issues?

Does the presence of Aeroshell grease on the threads make this whole topic irrelevant?

I don’t think I’ve ever seen this topic discussed.

 

[USK308]

I just finished building my 8.6BLK SBR. The barrel nut on this rifle was probably one of the best fitting barrel nuts I have put on any of my AR platform rifles. Excellent threads and a solid fit meant that when I torqued to 35ft-lbs, I had full surety that the barrel wasn't going anywhere (thus [hopefully] ensuring good accuracy as a whole).

From a pure engineering perspective, when you have quality threads that ensure good fit between upper and the barrel, I do think that will enhance accuracy, but that is just the opinion of this old geezer [lol].

 

[johnnyvw]

I would try a different barrel nut (or two) to see if it fits better. Like anything else mass produced, there's no guarantee the threads are correctly made.

I would think the fit between the barrel extension and the upper would have more of an effect...