Staking a barrel nut

[USAF_Vet]

So as I was mounting the barrel to an upper this weekend, I got to thinking why there are no instructions for staking a barrel nut. It seems like it should be done, but nope.

I've had some barrel nuts that needed a shim to fall into the 30-80 foot pounds of torque range. Being out of shims, the barrel nut I installed just simply would not line up in that torque range, at all, not anywhere close.

I ended up using a different barrel nut, which lined up great and torqued properly, so crisis averted, but it got me to thinking that if I had no other choice, could I have staked it into place? Google yielded nothing, neither did my old M-16 manual/ training/ reference book.

How would one go about staking a barrel nut, or is it something that shouldn't be recommended?

 

[bearcreek]

Sometimes there's a good reason something is not normally done. I'm thinking this would fall into that category.

 

[MistWolf]

Gas tube is the mechanical lock for the barrel nut.

If you cannot achieve the correct torque, thread locker is useless

 

[Theohazard]

MistWolf hit the nail on the head. The whole point of staking is to prevent a part from unscrewing loose. But the barrel nut is prevented from loosening by the gas tube. So staking the barrel nut is pointless.

 

[Ibmikey]

I know of no provision for staking a barrel nut or as stated above there is no need for same. I normally do not stake my castle nut on the receiver extension as I change these rifles around quite often. If the rifle was intended to never have changes I would stake it lightly, not being in a combat mode my needs are different than the military.

 

[carbine85]

I know of no provision for staking a barrel nut or as stated above there is no need for same. I normally do not stake my castle nut on the receiver extension as I change these rifles around quite often. If the rifle was intended to never have changes I would stake it lightly, not being in a combat mode my needs are different than the military.

^^ This is correct ^^ Never stake the barrel nut. The only parts that need proper staking is the gas key. Proper torque specs have held mine together for a long time.

 

[USAF_Vet]

The question was in reference to a barrel nut that could not be properly torqued and had no shims available.

It's probably not a situation most people are likely to be in, but in lieu of applying too much or too little torque, could a barrel nut be staked?

It's a hypothetical question, but the situation almost applied in this build. As I mentioned, I had an extra barrel nut that lined up properly with my receiver, and used that.

 

[dogmush]

What would the staking accomplish in that scenario?

Staking is just a mechanical way of holding a part. As was mentioned the gas tube holds the barrel nut, so staking is redundant on any build that uses a gas tube.

Barrel nuts have a pretty huge torque range. If I couldn't get one of the grooves to line up in that range, that would be a sign to me that something was out of spec, and I'd want to start taking careful measurements.

 

[carbine85]

The question was in reference to a barrel nut that could not be properly torqued and had no shims available.

It's probably not a situation most people are likely to be in, but in lieu of applying too much or too little torque, could a barrel nut be staked?

It's a hypothetical question, but the situation almost applied in this build. As I mentioned, I had an extra barrel nut that lined up properly with my receiver, and used that

I think the only correct way to fix this problem is use another barrel nut as you mentioned and replacing the out of spec upper or barrel is too expensive. I had one that was extremely tight so what I did was tighten and loosen over and over until I could line up the gas tube hole and stay within spec. Did you use a thread lubricant or anti-seize compound?

 

[Theohazard]

The question was in reference to a barrel nut that could not be properly torqued and had no shims available.

I still don't understand what staking would accomplish that the gas tube wouldn't. Again, the purpose of staking is to keep something from unscrewing on its own. But the gas tube already does that. Therefore, regardless of whether the barrel nut can be properly torqued or not, staking it is useless and accomplishes absolutely nothing.

 

[rbernie]

Not only that, I'm left wondering what you're gonna stake it to - the aluminum receiver?

 

[ApacheCoTodd]

If one can not "make it" to the next cut-out...

back it off.

These are what - 18 degrees apart?

Another thing to do is make certain the threads are clean.

Assembling on dry threads with significant residual powdered anodizing to the receiver and significant residual phosphating to the nut will yield ultimately inaccurate readings too.

Thread, un-thread, clean; barrel extension, nut and receiver and give it another go.

For my part, having assembled many hundreds of receivers, I have yet to use a torque wrench though it's not a bad thing... just haven't needed one and most people don't account for the leverage mutiplier of hanging a wrench off a barrel nut tool anyhow.

Todd.

 

[Tirod]

First, there is no "proper torque" to get the barrel nut to - it's a range of 30 to 85 foot pounds maximum.

Reread that TM: the upper limit is to prevent stripping the threads off the nose. It's not a "recommended torque," entirely because it getting the gas tube to pass the teeth can be done at any of 55 other different torque values.

If it can't or won't get indexed to the position to pass the gas tube from 30 to 85 foot pounds, shim it, lap the nose slightly, get a different nut, whatever. It's not about proper torque at all, it's about not screwing it in so tightly it removes the threads from the nose. Steel nut vs aluminum upper, the steel nut will win every time.

Good luck getting a "proper torque" and having it index correctly, too. Unnecessary and extremely difficult. It's why there are so many teeth on it - if it could be done, there'd be only one gap and it would always be up.

 

[justin22885]

staking would leave very little pressure in relation to torquing down the entire barrel nut, considering how big around the barrel nut is, any staking is going to have minimal effect and torquing the barrel also tightens it against the receiver to ensure it remains accurate.. if its not properly torqued the accuracy will likely suffer so staking is pointless, just replace the upper, barrel nut, or both as these components are fairly dirt cheap and as others have said... its aluminum, it wont take to staking so well

if you dont do it right the first time you'll just be doing it over later

 

[USAF_Vet]

I think the only correct way to fix this problem is use another barrel nut as you mentioned and replacing the out of spec upper or barrel is too expensive. I had one that was extremely tight so what I did was tighten and loosen over and over until I could line up the gas tube hole and stay within spec. Did you use a thread lubricant or anti-seize compound?

Yes, I use anti-seize on all my builds.

I probably had an out of spec barrel nut. First time I've encountered this, so I was just checking to see if there were alternate methods to ensure it wouldn't back out.

 

[MistWolf]

...most people don't account for the leverage mutiplier of hanging a wrench off a barrel nut tool anyhow

The spec in the manual includes the added arm of the barrel nut tool

 

[MistWolf]

First, there is no "proper torque" to get the barrel nut to - it's a range of 30 to 85 foot pounds maximum

There is a proper torque for the barrel nut. When the barrel nut is torqued within the specified range and correctly aligned, the requirements of the manual have been met and proper torque has been achieved

 

[ThePenguinKnight]

If torqued to at least 30 ft lbs, the nut should not be able to back off regardless of gas tube. If it's loose enough that the gas tube is the only thing keeping it from unscrewing, you'll almost certainly have accuracy issues.

There are an awful lot of handguards that use custom barrel nuts that have no gas tube teeth, yet have no issue staying tight.

I don't think staking aluminum to steel would be much good, unless you're ok with a barrel nut so loose that your barrel would be flopping around in the upper.