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

[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

 

[Hohn]

you still have YIELD all wrong. look up elastic deformation

A ding in a neck is not elastic deformation. By definition.

 

[6bra1k]

A ding in a neck is not elastic deformation. By definition.

that comment has nothing to do with the context
you are still missing a lot of science in your opinion...

 

[Dave M.]

I personally feel heavier neck tension is completely underrated. I’m always using between 2.5-4 thou.
Dave

 

[Dave M.]

A ding in a neck is not elastic deformation. By definition.

Correct, that would be INelastic deformation

 

[Dave M.]

Very interesting reading . I'm not in the same league as you all but my thinking is the same . I'm shooting 308 , my groups are 1/2 inch at 200 yards not 600 , that's amazing . I use to use the same brass until I saw a problem then dump them all , average 23 reloads . This season I'm trying 3 different lots 30 each , nothing fancy , HSM ,FC and ADI . I don't neck turn or add heat to the brass . I'm wet tumbling now brass comes out like new every time , add Imperial dry graphite lube to the bullet when seating . So far the case strength or the lubed seating is making a difference for the better . I was going down that road like you all but I don't think I'm capable of shooting those micro groups . I stopped over thinking kept it simple for my ability but love reading about what the real tight groupers do . Great Reading , thank you all.

Chris

Stop wet tumbling. Especially wet tumbling with pins. It’s doing ZERO for your accuracy.