.001 neck tension for .308 F-TR load?

[paulT]

only one way i know of to know how consistent your neck tension is and that is an arbor press with some sort of seating force indicator gauge. otherwise you are just guessing. i got the 21st century shooting hydro press. Quite an enlightening experience for me.

Using the standard force pack for the K&M Arbour press with a Wilson seater die what reading range on the dial indicator would indicate seating force ranges from 1 to 2 and 3 thousands in neck tension in correlation with the bullet seating force with new .308 lapua brass.

 

[fatelvis]

I have used .001” neck tension in my single shot rifles with great success, but when using an auto loader, I have caught the tip on the front of the magazine unknowingly when loading, and wrecked a couple really good scores because of it! .002” minimum tension on an AR cartridge for me, better yet .003”.

 

[D-4297]

Wonder how some would react to setting cases up for only .0005 interference fit ? I know some who you can spin the bullet in their cases , literally . And their names would shock many on here .

 

[Ned Ludd]

Wonder how some would react to setting cases up for only .0005 interference fit ? I know some who you can spin the bullet in their cases , literally . And their names would shock many on here .

I know one of them. Her name is Lucie Bullet.

 

[D-4297]

Oh ; You know a couple of them , Ned . Some "refer" to the process as "soft seating" .

 

[paulT]

Oh ; You know a couple of them , Ned . Some "refer" to the process as "soft seating" .

Havent soft seated bullets for years due to a cease fire been called during a match and upon round extraction left powder lodgged in behind bolt locking luggs that even a can of air couldnt dislodge.

 

[Hohn]

It seems to me that beyond some amount of interference, you cannot actually increase neck tension because either the neck will yield or the bullet will or both to varying degrees. The material properties sheets strongly suggest that the bullet will yield before the neck does. Even annealed, the brass has a 44ksi yield point. Lead is less than half of that. Damon Cali's excellent article (linked in a previous post) shows that phenomenon of neck yield occurs with relatively low amounts of interference fit.

I am curious of some of the observations we attribute to neck tension are actually artifacts of the process used to achieve some given neck tension. For example if you use a Collet die vs an Expander Mandrel and have the same neck OD measurement before seating, do you actually have the same seating *force*? I suspect close, but not the same. The surface finish/friction in the neck matters. Neck tension just provides the "normal force" but the coefficient of friction is the other half of the equation, so BOTH are pivotal in determining final seating force. I suspect that the force to dislodge the bullet actually is what matters-- not so much the neck tension that delivered that force.

 

[Richard Coody]

It seems to me that beyond some amount of interference, you cannot actually increase neck tension because either the neck will yield or the bullet will or both to varying degrees. The material properties sheets strongly suggest that the bullet will yield before the neck does. Even annealed, the brass has a 44ksi yield point. Lead is less than half of that. Damon Cali's excellent article (linked in a previous post) shows that phenomenon of neck yield occurs with relatively low amounts of interference fit.

I am curious of some of the observations we attribute to neck tension are actually artifacts of the process used to achieve some given neck tension. For example if you use a Collet die vs an Expander Mandrel and have the same neck OD measurement before seating, do you actually have the same seating *force*? I suspect close, but not the same. The surface finish/friction in the neck matters. Neck tension just provides the "normal force" but the coefficient of friction is the other half of the equation, so BOTH are pivotal in determining final seating force. I suspect that the force to dislodge the bullet actually is what matters-- not so much the neck tension that delivered that force.

It seems many on this forum want to get into all these engineering terms. Frankly i have an engineering degree and know with neck tension there are way too many variables to calculate with any accuracy.

I say consistent neck tension is probably more important then the actual forces involved. The reason i say this is i can see it on the target. Before getting a 21st century hydroseater i thought i had consistent neck tension. Boy was i wrong. Learned a lot about what it takes to get consistency and once i did it showed on the target.

You have to find what works for you and your rifles.

 

[Hohn]

It seems many on this forum want to get into all these engineering terms. Frankly i have an engineering degree and know with neck tension there are way too many variables to calculate with any accuracy.

I say consistent neck tension is probably more important then the actual forces involved. The reason i say this is i can see it on the target. Before getting a 21st century hydroseater i thought i had consistent neck tension. Boy was i wrong. Learned a lot about what it takes to get consistency and once i did it showed on the target.

You have to find what works for you and your rifles.

Can't disagree there, I think we're on the same page.

 

[Ned Ludd]

It seems to me that beyond some amount of interference, you cannot actually increase neck tension because either the neck will yield or the bullet will or both to varying degrees. The material properties sheets strongly suggest that the bullet will yield before the neck does. Even annealed, the brass has a 44ksi yield point. Lead is less than half of that. Damon Cali's excellent article (linked in a previous post) shows that phenomenon of neck yield occurs with relatively low amounts of interference fit.

I am curious of some of the observations we attribute to neck tension are actually artifacts of the process used to achieve some given neck tension. For example if you use a Collet die vs an Expander Mandrel and have the same neck OD measurement before seating, do you actually have the same seating *force*? I suspect close, but not the same. The surface finish/friction in the neck matters. Neck tension just provides the "normal force" but the coefficient of friction is the other half of the equation, so BOTH are pivotal in determining final seating force. I suspect that the force to dislodge the bullet actually is what matters-- not so much the neck tension that delivered that force.

If you have the means to cover a small range of neck tension (interference fit), there are some simple experiments you can easily do to convince yourself whether the above statement is true over the range of neck tension we typically use. For example, if you have the necessary bushings, you can load up a few [otherwise identical] rounds each at .001", .002", .003", and .004" neck tension. First, pay close attention to how much force is required to seat the bullets. If you can feel a difference, it's probably a significant difference. Then you can measure velocity for the loaded rounds to determine whether there is any difference in velocity and/or grouping on the target. This is probably a good experiment for anyone that is unsure of whether we are actually changing neck tension over the typical range used, or how much of an effect it may have. Testing in your own hands is never a bad idea.

 

[paulT]

It might blow some minds,but in my most accurate and winning 308 barrel, 0.007 interference fit was the most accurate. Not only did I validate this multiple times, but it continues to shoot lights out after 3050 rounds. I have some theories about this, but the target has the final say. Drew

Which powder & bullet was used with your .308 Loads.

 

[Hohn]

This is not a question anyone can answer for you. There are many variables that effect whether a combo will want light or heavy neck tension. And even knowing all of those, you still have to test it to know for sure.

This. Foremost is neck hardness imho. But it’s not just one thing.

 

[6BRA]

a mandrel will yield .001 more tension than marked mandrel/ a bushing will yield .001 less than marked bushing. Spring back even if annealed there is some spring back. Just depends on if you are sizing from inside or outside.

 

[6bra1k]

It seems to me that beyond some amount of interference, you cannot actually increase neck tension because either the neck will yield or the bullet will or both to varying degrees. The material properties sheets strongly suggest that the bullet will yield before the neck does. Even annealed, the brass has a 44ksi yield point. Lead is less than half of that. Damon Cali's excellent article (linked in a previous post) shows that phenomenon of neck yield occurs with relatively low amounts of interference fit.

.

the problem with having some facts is that they can be misapplied.
this statement while old ,is very wrong in the bullet seating world

 

[Alex Wheeler]

I think neck tension is one of the main things holding back many shooters. There is the idea that you just pick a certain amount like .002 and just go with it. That is no different than picking a seating depth or powder charge and never testing it. NT can prevent a rifle from EVER tuning up. If you shoot a bushing test from .001-.005 of neck tension you will see a change with every one. Even past .005 you will see changes. I just dont remember anyone going past .005 for best accuracy. But if I had to pick one neck tension for everything for the rest of my days without testing it would be .005". At least at long range. I have never tested it at short range.

 

[6bra1k]

my OPINION is the neck tension is less important if you are at or in the lands.
other than that it is a tuning variable like all else

 

[Hohn]

the problem with having some facts is that they can be misapplied.
this statement while old ,is very wrong in the bullet seating world

I’ll accept I’m in error if it can be shown. But you’ll need to do better than just saying “you’re wrong.”

 

[6bra1k]

I’ll accept I’m in error if it can be shown. But you’ll need to do better than just saying “you’re wrong.”

take your thumb nail and ding the neck of a case at the mouth.
most rifle match cases run from .008 to .015 thick, and can be dinged with a thumb nail
do you really think that is 40kpsi ???
your numbers and terms are OUT OF CONTEXT.

 

[Hohn]

It seems to me that beyond some amount of interference, you cannot actually increase neck tension because either the neck will yield or the bullet will or both to varying degrees. The material properties sheets strongly suggest that the bullet will yield before the neck does. Even annealed, the brass has a 44ksi yield point. Lead is less than half of that. Damon Cali's excellent article (linked in a previous post) shows that phenomenon of neck yield occurs with relatively low amounts of interference fit.

I am curious of some of the observations we attribute to neck tension are actually artifacts of the process used to achieve some given neck tension. For example if you use a Collet die vs an Expander Mandrel and have the same neck OD measurement before seating, do you actually have the same seating *force*? I suspect close, but not the same. The surface finish/friction in the neck matters. Neck tension just provides the "normal force" but the coefficient of friction is the other half of the equation, so BOTH are pivotal in determining final seating force. I suspect that the force to dislodge the bullet actually is what matters-- not so much the neck tension that

take your thumb nail and ding the neck of a case at the mouth.
most rifle match cases run from .008 to .015 thick, and can be dinged with a thumb nail
do you really think that is 40kpsi ???
your numbers and terms are OUT OF CONTEXT.

Ah, you got me to go back and reread my post and it was mistaken. Thanks for catching that.

Yes, if a neck has a yield strength of 40ksi and you ding it, you exceeded 40ksi. It’s a tautology.

I don’t know why I posted that a neck would yield a bullet, I know this to be wrong and I think that’s what you caught.

What I meant to say was that once you yield the neck, more tension can hardly be achieved because metallurgy is determining neck tension more than geometry. This is why torque to yield screws are used-to eliminate the tension variation of straight torque.

Anyway, thanks for catching my error, I appreciate your patience.

 

[6bra1k]

Ah, you got me to go back and reread my post and it was mistaken. Thanks for catching that.

Yes, if a neck has a yield strength of 40ksi and you ding it, you exceeded 40ksi. It’s a tautology.

I don’t know why I posted that a neck would yield a bullet, I know this to be wrong and I think that’s what you caught.

What I meant to say was that once you yield the neck, more tension can hardly be achieved because metallurgy is determining neck tension more than geometry. This is why torque to yield screws are used-to eliminate the tension variation of straight torque.

Anyway, thanks for catching my error, I appreciate your patience.

you still have YIELD all wrong. look up elastic deformation