Loose barrel

[Cmgoff]

But if you increase the coefficient of friction you generally only increase the torque required to achieve the same clamp load. Two joint with different coefficient of friction and equal clamp load will function more or less the same assuming traditional application. In the case of the barrel nut, I would suspect the nut has seen too many cycles and it jumps threads during torqueing or shooting. To prevent the barrel nut from coming loose we need enough clamp load to compress the threads more than the chamber pressure tries to stretch the barrel, if this is true then summing our forces always yields clamp load.

Sent from my Pixel using Tapatalk

[RustyShackle]

This is an incorrect ststement. I too am an engineer and I also manage a fastener testing Lab. You are correct that most of the torque applied is wasted overcoming the friction forces. The misconception is that friction prevents the joint from loosening. Actually the stretching of the components ( traditionally the bolt but in our case the threads in the nut) act as a spring and keep the joint closed. You could say that the sping applies s normal force to the surfaces and therefore friction is still reasponcible for keeping the joint closed

Sent from my Pixel using Tapatalk

No, that is not an incorrect statement. Friction does prevent the joint from loosening, which is accomplished via the compression/tension that is applied from the fastener being tightened. The important part to remember here is that the friction is made possible by the compressive load from the barrel nut/receiver face, applied by the tension from the barrel. Otherwise a roller bearing between the mating surfaces should not matter! And if there were roller bearings between the thread mating surfaces and the union it would freely spin, even under relatively high torque values.

Its really no different in terms of physics than loading weight onto a sled and the more the load increases the larger the force needed to overcome the friction required to make it move. The friction coefficient in this example and the barrel example remain the same. So the torque value only changes with the applied normal force

[RustyShackle]

Another way to think of this, is, with standard helical threads on a bolt(barrel), is that in reality they are a ramp, or inclined plane. The nut, or in reality the threads of the nut sit on this inclined plane. The only thing that holds the nut from sliding down the plane is the friction between the two. Applying force along the axis of the bolt increases the total force required to overcome this friction. Depending on the modulus of elasticity of the material and the yield strength determines how much force can be applied before failure from plastic deformation occcurs and the compressive/tension force holding the two surfaces is lost.

[RC20]

Better cheap insurance than no insurance. I do agree that nickel would be the best choice when it comes to stainless. I have used copper, black moly, and nickel based anti-seizes when mounting barrels. I cannot say that any work better than another but I can say I have never had a barrel come loose nor removed requiring excessive force.

Frankly, there is a difference between cheap and wrong.

If you have a heart condition and get insurance for a brain tumor and croak, that does the survivor no good.

Mr. Furious has pointed out that the factory uses nothing (other then left over residue from tumbling the barrel and that is an accident of the process)

Maybe the best example of wrong but perceived as insurance was (still are?) those magical claims of being able to run you engine without oil.

Actually it works and you can (test by the USAA in WWII for oviousl reason)

The problem?

Its a chlorine based, said chlorine base lube attacks lead bearings like there is no tomorrow.

So, if you loose your oil before the bearings are destroyed, it will save you.

Unfortunately its a pretty narrow window and your engine is most likely going to quit on the other side of the German border.

I had some experience with TFE? back in the day. The good news was the engine I chose to put it in had lots of clearance and did not cause any problems.

The bad news was that people with more intricate engines (Japanese, European ) has passages clog up and oil starvation to important parts.

[Blackthorn]

I think we need to step back and gain some perspective. I would not run my BMW without the recommended oil or lubricants. My rifles on the other hand are another matter. I agree with Mr Furious in regards to Savage not using any type of anti seize. I shot with a number of Savage employees and engineers (one of the main reasons I shoot Savage rifles) at the Westfield Sportsman's Club while living in Springfield, MA. I have had this discussion with them and they do not apply anything during assembly. From a manufacturers stand point applying what they must figure an unnecessary compound to the assembly process would affect the bottom line and the bottom line is king.
That being said I am a competitive shooter and a brick and mortar graduated gunsmith. I tend to roll my barrels more than most. I have been through 3 barrels on my first F-Class rifle and have 1500 on my second F-Class in two seasons. I use copper on my AR builds and abuse them regularly. I have used various different anti seizes on barrel changes and have not had any problems. Until I see something that would cause me concern I will continue using something than nothing.

[RC20]

Well I see plumbers use Teflon tape, dope and have even seen Permatex used on flare fittings.

It doesn't hurt for the most part, it can mess up the seal as well.

My only reasons to use what I do is I prefer a smoother joint, and the torques setting is predicated on a lubed joint.

Savage clearly has it figured out its not needed for correct and lasting assembly.