Barrel Nut Disadvantages?

[mikecr]

Well, you can read 'Rifle Accuracy Facts' to learn about barrel connections, and consider what IS BEST.
What people have been doing for over 200yrs means nothing about best. It's just what people have been doing for 200yrs.

Studs provide a better connection than bolts, because they engage all threads at once, where bolts typically engage only the first few threads. But, read that book. Really

 

[Darwin]

Shot my IBI prefit at 1k for the second time Wednesday, three feet of drift. Off a tripod so I only managed three good sight pictures, 36x shows all lol. Tripods are hard.

 

[INTJ]

Well, you can read 'Rifle Accuracy Facts' to learn about barrel connections, and consider what IS BEST.
What people have been doing for over 200yrs means nothing about best. It's just what people have been doing for 200yrs.

Studs provide a better connection than bolts, because they engage all threads at once, where bolts typically engage only the first few threads. But, read that book. Really

I have a copy of Rifle Accuracy Facts. I got the book after it first came out. There is some good stuff as well as some outdated and inaccurate information.

While a nut on a stud does a good job with thread engagement and load, it is weak on alignment and horizontal support. I'd much rather have three or four threads providing the clamping force and allow a machined shoulder to firmly contact a trued receiver face for barrel alignment and support.

When it comes to a no-compromises shooting competition like LRBR, it doesn't matter what people have done for 200 years. All we care about is shooting small groups and high scores, and do whatever it takes. We have tried all manner of tools and approaches, that most have never thought of. If it works we keep it, if not we discard it.

If barrel nuts were better we'd all use them--period.

And while theory is nice, here are some actual results. These are all 10-shots fired at 1000 yds, during registered matches. Groups sizes range from 3.855" to 4.9" from a shouldered barrel. And I have more targets with similar groups, but I quit taking pictures of them a while ago.

All that has to be done to change my mind is for barrel nut rigs to show up at matches and frequently outshoot shouldered barrels.

 

[urbanrifleman]

 

[Alex Wheeler]

Rifle accuracy facts is a good book. Lot of work went into it. But its no longer a useful reference in todays world. Simply put, a .270 sporter barrel was used for the testing. And some of the conclusions in my opinion were came to because of poor accuracy and poor testing methods. Like the whole chapter on the barrel thread moving. The test device in my opinion was where the movement came from. I can say this because over the years I have used many greases and the rifles have set records on most all of them. If there was any movement in the joint we would know.

 

[urbanrifleman]

I have a copy of Rifle Accuracy Facts. I got the book after it first came out. There is some good stuff as well as some outdated and inaccurate information.

While a nut on a stud does a good job with thread engagement and load, it is weak on alignment and horizontal support. I'd much rather have three or four threads providing the clamping force and allow a machined shoulder to firmly contact a trued receiver face for barrel alignment and support.

When it comes to a no-compromises shooting competition like LRBR, it doesn't matter what people have done for 200 years. All we care about is shooting small groups and high scores, and do whatever it takes. We have tried all manner of tools and approaches, that most have never thought of. If it works we keep it, if not we discard it.

If barrel nuts were better we'd all use them--period.

And while theory is nice, here are some actual results. These are all 10-shots fired at 1000 yds, during registered matches. Groups sizes range from 3.855" to 4.9" from a shouldered barrel. And I have more targets with similar groups, but I quit taking pictures of them a while ago.

All that has to be done to change my mind is for barrel nut rigs to show up at matches and frequently outshoot shouldered barrels.

View attachment 1427249View attachment 1427250View attachment 1427251

Tubb's ATR action will probably outshoot anything on the planet (this is my opinion) yet not "everyone would be shooting it" really is true. I am sorry, no offense, but that idea is a bit silly. His action uses a barrel extension on the barrel. No one is using that tech. In fact, there is laundry list of innovations in his action . Some of which are TRULY game changers in design. Patented. Innovations.

In my opinion, most of the other actions are basically modified Mausers by comparison... I know... I know... How controversial to imply that nearly ZERO innovation has really occurred in bolt action actions in 150 years, but it is true. They still look nearly identical to the original. Certainly improved, but not really any different. I doubt there are any substantial patents floating around on bolt actions being used today because few updates being used today is patent able as unique.

And the idea that how the pipe thread is tightened on the barrel is some kind of game changer seem kind of silly to my brain, which was a mechanical engineer designer brain for 25 years. But hey, lots of people buy unsubstantiated theories.

And I really do think most of the stuff bantered about these days is just marketing. People marketing their products. "Oh mine's better because of yada yada yada", or "that guy sucks because of blah blah blah".

Marketing.

I let my nut barrels do their own talking. I find results outweigh theory.

 

[mikecr]

Vaughn's finding was that standard barrel threading unloads considerably under firing pressure. That tightening that kind of connection ever higher, consistently helped (with his results). I believe he went up way higher in torque than is common.

Then he went into a different kind of threading system that spread the loading across more threads, and he found that extreme tightening was no longer needed. This is just what a fine threaded tenon tightened with a barrel nut does. And you can go finer threading while employing less tightening force.
I would rather have fine/shallow threading around the chamber than coarse/deep threading.

The direction of tension comes into this as well.
Pre-tensioning is stretching within modulus of elasticity.
A bolt/shoulder connection pre-tensions with the first few threads, toward the bolt face.
A stud/barrel nut connection pretensions with all threading at once, away from the bolt face.
Firing pressure pushes/stretches the barrel outward. Albeit a very small amount.

With a shouldered connection, and tightening ever more, the threading behind those first few taking all the load is pulled toward the bolt face. A weird front-side loading. On firing, those threads snap the other direction, towards their back-side, for a time unloading.

With a nut, and tightening ever more, all barrel threading in the action ring is pulled by the nut together to it's back-side. With this condition set, firing pressure is spread across all threads in the action ring in the same outward direction, increasing load on them (not unloading).

I am not a competitor, nor a mechanical engineer, I don't have barrel nuts in current guns, but this all makes sense to me.

 

[danny]

I think for most applications a good quality barrel nut on a well machined barrel ought to be okay. However, as I think through this, I see some potential disadvantages.

With a well machined shouldered barrel, when you tighten it up it firmly and evenly engages the action. At most, you might get .001" more from just snug to heavy torque. More often I think it's less than .0005". This means the barrel is true to the action with no stress. This allows very heavy barrels to free float.

With a barrel nut, there is no barrel shoulder so thread tension must be what holds everything in place. The threads on the nut will stretch a little as will the threads on the barrel. They will have to stay in tension to keep the barrel nut square against the shoulder, so there will always be stress and the heavier the barrel the more the stress.

I suppose the only place where we would see any issue might be in SR BR or LR BR when conditions are excellent.

What have you guys seen?

Barrel nuts are ugly. I do not care if there is any advantage. Somebody once said "It is better to look good than it is to be good", and I generally believe that. However, I always add "looking good and being good can be the same thing".

Danny

 

[urbanrifleman]

Barrel nuts are ugly. I do not care if there is any advantage. Somebody once said "It is better to look good than it is to be good", and I generally believe that. However, I always add "looking good and being good can be the same thing".

Danny

This is what I find to be the case, that most people complain about looks. If they don't like the look suddenly they don't shoot as well...haha

 

[danny]

It is very simple, if you never intend on removing the barrel until it is shot out go the shoulder route.
If you intend on removing it to swap barrels or for whatever reason, then you should go the barrel nut.
Me I like my Barrel Nuts.

Exhibit A

Dean View attachment 1227497

I just swap rifles.

Danny

 

[GenePoole]

Vaughn's finding was that standard barrel threading unloads considerably under firing pressure. That tightening that kind of connection ever higher, consistently helped (with his results). I believe he went up way higher in torque than is common.

Then he went into a different kind of threading system that spread the loading across more threads, and he found that extreme tightening was no longer needed. This is just what a fine threaded tenon tightened with a barrel nut does. And you can go finer threading while employing less tightening force.
I would rather have fine/shallow threading around the chamber than coarse/deep threading.

The direction of tension comes into this as well.
Pre-tensioning is stretching within modulus of elasticity.
A bolt/shoulder connection pre-tensions with the first few threads, toward the bolt face.
A stud/barrel nut connection pretensions with all threading at once, away from the bolt face.
Firing pressure pushes/stretches the barrel outward. Albeit a very small amount.

With a shouldered connection, and tightening ever more, the threading behind those first few taking all the load is pulled toward the bolt face. A weird front-side loading. On firing, those threads snap the other direction, towards their back-side, for a time unloading.

With a nut, and tightening ever more, all barrel threading in the action ring is pulled by the nut together to it's back-side. With this condition set, firing pressure is spread across all threads in the action ring in the same outward direction, increasing load on them (not unloading).

I am not a competitor, nor a mechanical engineer, I don't have barrel nuts in current guns, but this all makes sense to me.

I usually don't like to get bogged down in these "thought experiment" type threads.

In my mind, it works the opposite. I look at the ideal as being an action and barrel as a single piece of metal. That's not practical, so you have to thread on the barrel. You've decreased the ideal by a factor of one threaded joint. Now put a nut on it and you've decreased the ideal by two threaded joint factors.

That said, my Savage 10 .223 with stock barrel shoots better than a Panda F-Class 223 with a Bartlein barrel, but that's an anecdote, not a datum.

 

[rijndael]

It's interesting that the comparison is never put forth in the opposite direction. No one ever asks if a shouldered barrel can be as good as a barrel nut.

 

[scope eye]

I just swap rifles.

Danny

I would have a total of 96 rifles instead of 1 rifle with 4 barrels each, a 5 gallon bucket is cheaper then all the safes I would need. Which leaves me with more money to buy more Barrels , See how that works.

 

[BoydAllen]

In Vaughn's book he mentions a couple of schemes to impeove barrel action joint stability, that are applicable to regular actions, tapered threads and a special thread shape that is patented (You might want to ask Greg Tannel about the latter, as he has used it a lot.). On the former, my early Viper was intentionally made with thread taper to spread the load down the tenon. Later that feature was abandoned, probably because smiths were used to, and preferred parallel threads. Nevertheless the taper actually works. One thing that shooters may not appreciate is that the lateral load is pretty much entirely handled by the face of the action, rather than the tenon threads whose primary function is to load the face of action contact. What Vaughn found was that under the pressure of firing that the expansion of the front receiver ring and tenon could effectively nullify the tension for an instant. He also said that for benchrest guns the heavier weight barrels and smaller calibers probably made this an non issue. A friend has done extensive bullet prototype testing with nutted barrels, with good results, but that was with a rail gun which means a lot less stress on the action barrel to action joint, and the barrels were heavy, and the caliber relatively small. The only issue that I can see for careful range use, is that the nut system is basically incompatible with glued in actions, but for other bedding systems, I do not think that it would result in inferior accuracy, or advantage. What is does do is allow a shooter to fit his barrel without a smith or lathe being required. If you are swapping barrels a lot I would choose a shoulder, but if you put one on and leave it, then I think that either would be fine. I have shot both.

 

[jds holler]

My brain has been troubling with the problem of the barrel "pointing" at an undesirable (or any) direction from the receiver. So I've invented a solution. Tell me whatcha think. --

How about two thin precision shim-washers, say around .015 thick. They aren't flat, but tapered from one side to the other. (maybe about .002 difference)
These washers go between the barrel nut, and the receiver face, and the relationship they have with each other would allow anywhere from +.004" to .000" on any location desired on the nut/barrel to receiver joint.

Of course this would effect head-space on a shouldered barrel -- but be simply adjusted to fit with a nut system. I realize this would involve more set-up time when installing a barrel, but also offers a correction for "barrel pointing".

I offer my idea for your consideration and criticism. Frankly I'd be amazed if it hasn't already been done. jd

 

[mikecr]

In my mind, it works the opposite. I look at the ideal as being an action and barrel as a single piece of metal. That's not practical, so you have to thread on the barrel. You've decreased the ideal by a factor of one threaded joint. Now put a nut on it and you've decreased the ideal by two threaded joint factors.

Good thinking. Actual thinking.
I see the point of influence between them as the same. Both stop at the action face.
It's just one stop is pulling all threads to backside thread contact.
The other, just opposite.

Between bolt -vs- stud connection, or bolt head tightening -vs- nut tightening, I'm pretty sure a stud is superior.
This, with multi-industry electrical/mechanical/civil construction perspectives.
Not competitive shooting.

 

[SKWERLZ]

This is what I find to be the case, that most people complain about looks. If they don't like the look suddenly they don't shoot as well...haha

I don’t do Instagram coffee table gun pics(especially now that they deleted my account) so I never prioritized rifle fashion over function.
Back before I started doing my own barrel work I exclusively bought barrel nut prefits, now I do mostly shouldered barrels as I have full control on headspace and like the extra challenge of timing the barrel end extra steps for a shoulder.
I do like the extra weight you can get with a shouldered barrel as well for my 338.

 

[urbanrifleman]

I don’t do Instagram coffee table gun pics(especially now that they deleted my account) so I never prioritized rifle fashion over function.
Back before I started doing my own barrel work I exclusively bought barrel nut prefits, now I do mostly shouldered barrels as I have full control on headspace and like the extra challenge of timing the barrel end extra steps for a shoulder.
I do like the extra weight you can get with a shouldered barrel as well for my 338.

My personal rifles are shouldered as I also like the weight. Same blanks shoot the same with a nut.

 

[swd]

Building a one piece barrel/action as an experiment would answer a lot of questions. But that comes with its own problems to overcome like heat treat.

Personally I don’t think there’s a whole to gained worrying about barrel threads. There have been guys overthinking barrel threads for 50 years.

 

[jackieschmidt]

The M18 Mauser and I think one of the Sig Rifles have the locking lug abutments in the barrel.
But these are strictly hunting rifles.

I am tempted to take one of Benchrest Rifles, machine a barrel nut similar to the way Shilen does it, and see what it shoots like.

My Bat M is a bolt in, I suppose I could clearance the forearm in front of the action to clear the nut.