Brownells Gun Techs Caleb Savant and Steve Ostrem take on another item of the firearm world’s “received wisdom,” specifically the notion that an AR-15 barrel nut must be tightened to a precise torque setting to ensure best accuracy – and to keep the gun from blowing up. The recommended mil-spec torque setting is 30 to 85 ft.-lbs, which is a HUGE range. That’s like saying, “Not too loose and not too tight.” The range is so wide because the original-style M16 barrel nut, still found on many civilian AR-15s, has teeth on it that have to be rotated to provide clearance for the gas tube. Once you can get the gas tube through, you’re good, as long as you’ve applied more than 30 and fewer than 85 ft.-lbs. of torque. The rifle will shoot perfectly well. (NOTE: Some AR-15 manufacturers do call for more specific torque settings; you’ll want to adhere to those.) Got a firearm “myth” you’d like the guys to address? Let us know in the comments below.
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Thanks for all of the good information.
I thoiught the top end torque was to prevent stripping the receiver threads?
Great video
You can vary barrel nut torque as a way to tune barrel harmonics, similar to the way a smallbore shooter torque their action screws. Highpower service rifle builders have been doing it since the ar15 became popular in competition. You start at 30 and shoot a group then increase 5 or 10 ft-lbs and fire another group. For the barrel nut splines, set initial 30 lb torque and just cut off the adjacent spline so you don't have to worry about the gas tube. This method works well and when used in conjunction with tuning the flash suppressor can cut group size in half. I do these methods on a new barrel so I can tune the existing match ammo from a previous barrel, instead of working up new loads. I'm on barrel #3 on my latest rifle and still using the same load.
Help me out guys. I took a virgin upper and barrel to a gun smith and he told me I needed to buy shims for the standard barrel nut in order to get it to specks. Anyone familiar with this ?
Whats the deal with seasoning youre barrel threads?? i have never done it and ive never had any problems
Steve is the best. He's like my uncle, but a gunsmith. Caleb is like my barber, but a gunsmith.
Can you over torque a barrel nut ? Because I had to crank down on one harder than I wanted to. I was using arrowshell Or however you spell it
There’s another myth about the torque on the muzzle break or I guess y’all call em flash hiders these days
Im curious about leaving your magazines loaded.. I keep hearing a local Gun store work warning everyone not to leave their magazines loaded due to "Spring memory" , but have seen a few conflicting comments on the subject..
I’m curious to know why the 224 Valkyrie started off as a wonderful platform and then had trouble with some rounds and all of a sudden they disappeared where as far as I can tell the 2 24 is still just as good as people said it was going to be am I missing something or is the 2 24 Valkyrie still that good the reason I’m asking you just never see anything about it anymore
These guys are good
The hand guards have to time on that damn sprocket nut too. Hate those nuts! 😂
SAAMI and CIP, specifications for 9X19 standard pressures differ, why? Different measurement system? Are both safe in all weapons chanbered for this caliber? Is there an equivalent in CIP for +P and +P+? Are the imported munitions from Tula and others CIP or SAAMI? Is the head space the same for each on a 7.62X54?
Does someone make an actual torque wrench for this? Seems like 55 ftlbs would be the goal.
When I build mine I prefer to start at the lower end of the torque spectrum and if I have to take it apart for any reason I will re-install the barrel but at 1-5 lbs higher than the original setting if the original setting doesn’t index using the sprocket style barrel nut. If it does still index at the original setting and there is no play in the barrel I leave it alone. If I am using a barrel nut that doesn’t require indexing I will leave it at the lower setting as long as there is no play in the barrel.
0:34 I know a bit about torque. For a 1.25" 7075 t6 aluminum thread with a half inch of engagement, the torque rating is in the 375ftlbs range for UNC, 385 ftlbs for UNF, and probably near 400 ftlbs for the 1.25 UNEF thread of the ar15 barrel nut.
But the receiver threaded portion is hollow to accept the barrel extension, so we need to derate the torque quite a bit.
@30lbsft, that should be like 1500lbs of clamping force holding the receiver and Barrel together. @90lbsft its probably close to 4000lbs clamping force. But at that point you're getting less clamping force per torque due to the increase in the amount of torque required to overcome friction.
That means the threads can probably take 90 ftlbs before stripping. That’s insane
I was taught to tighten it 3 times. Tighten once, loosen. Tighten twice, loosen. 3rd time tighten to torque setting and good to go. This is on a New barrel nut.
You guys need a show with a fireplace in the background and just talk about guns for an hour!
The Colt manual does say 30-80, however per Colt Armorer’s course barrel nut install is as follows; torque to 30, loosen and re-torque to 40, loosen and final torque to 50. Apply additional torque to align gas tube if needed, do not exceed 80, all while using an anti seize. So min is 50, max is 80.
Just don't forget the anti seize on the threads….one of those things you'll only do once.
Please bring back fn barreled socom profile uppers with out the m203 cut !!!!!!! FOR FUCKS SAKE MAN !!!!!!!!!!!!
I built my AR-15 from random parts (no kit), and I did it all while sitting on my couch.
Only tools I used were an adjustable wrench (just that typical kind everyone owns with the thumb screw to set the jaws), just regular old pliers, a Philips head screw driver, an Allen wrench kit I've put together over the years, a simple castle nut wrench (weighs less than 0.5 oz. and was like $12), and finally, a proprietary tool that came with my Aero Precision ATLAS S-One hand guard.
Put her together in a little over an hour, as I'd never done it before. ARs are stupid-easy to build, and when it comes to tightening stuff, just use the standard rule of make it snug, but don't try to kill it, stripping its threads in the process. You tighten until it doesn't seem to move, then give it one last little bit of extra muscle. It's not like a car engine where you need very specific torque on parts due to incredibly tight tolerances, like when reattaching a piston rod to the crank. It's a gun, not a car. It's basically a tube that you generate pressure inside to push things out the end, lol!
My rifle shoots great, and I have no issues hitting a 8" popper from the bench at 450 yards. It ain't rocket science. I wasn't even wearing pants when I built it, ffs. I also don't use any adhesives, Loctite or otherwise. No need if you tighten things properly and inspect your rifle for issues while cleaning, which you really should do after each range visit, not because it needs the cleaning every time, but so you catch problems early. Preventative maintenance. At minimum, inspect your parts and run a bore snake through the barrel. Takes less than a couple minutes to do both, and a clean barrel is an accurate barrel.
Use nut shims so you can time without over torquing. Lets you torque for 45-50 for a good setting without potentially damaging the upper.
Or grind down the tab lol
The only time i ever had a barrel nut torque issue was with a carbon15 with the poly upper and lower. Complete piece of junk. I will never work on one again. A guy was trying to use it for a duty rifle i 3nded up getting it going but told him to get rid of it and get hin a decent rifle for that purpose
Tight is tight and broke is broke!!
So many variables in torque " I always use my torque wrench" – when was torque wrench last calibrated? = blank stare // what are the thread tolerances = blank stare // what kind of thread lube /anti seize are you using it makes a BIG difference = blank stare Thanks for trying to add some reason to the discussion.
Tighten it by hand.. you can probably get around 30-50 lbs torque
When I went to Armorer School by Colt they said "Here are some totally irrelevant numbers so we can say we taught it…… now just tighten by hand and then with a wrench until the next notch lines up for the gas tube".
The biggest Myth brought to us by the self appointed rulers of our opinions (media) A R stands for assault rifle…..
Busting the myth of no beverages on your work table
Is it acceptable that the gas tube makes ANY contact with the barrel nut? I have an Atlas R-One handguard that utilizes its own barrel nut and the gas tube makes a little contact with it.
Grease on the barrel nut threads?
What is the proper torque on a muzzle device or does it matter?
I'm curious to know what happens if the barrel nut isn't tightened with enough torque? If it's under 30, could it cause damage or injury?