Expanders prior to seating...

[mikecr]

The neck shoulder area of the brass is the most vulnerable to change. Expanding with the use of a ball or a push in expanded can do more harm than good. The case is not supported with the die . Consistent neck tension is done with neck thickness and elasticity of the brass - And or annealing.
Larry

Expansion should be seen as 'pre-expansion' or 'pre-seating', and is beneficial toward lower loaded TIR, consistent seating force(for consistent seating depths) and better tension consistency.

For tension, consider that tension is merely spring back against seated bullet bearing. Spring back is counter to last sizing action. That is, if your last sizing was inward, by quite a bit, spring back will be biased outward quite a bit(and we all know spring back varies).
Where you pre-expand with a mandrel(which is better for this than bullets) spring back is biased inward(more toward gripping). This spring back, either direction, continues over time until reaching lowest energy balance(part of the variance).

Now if you down size normally, spring back will open necks a small bit. If you follow with less expanding(than down sizing) you consume remaining down sizing energy and leave relatively less inward spring back energy out of balance. It's like halving the energy variance twice, to 1/4 that of down sizing alone.
It is possible to manage truly consistent neck tension without ever annealing, and this is a keystone action in that. This plan, including other actions, provides for much higher neck tension that is as consistent as process annealed.
There you have it, the tension advantage in neck pre-expansion.

 

[savagedasher]

Expansion should be seen as 'pre-expansion' or 'pre-seating', and is beneficial toward lower loaded TIR, consistent seating force(for consistent seating depths) and better tension consistency.

For tension, consider that tension is merely spring back against seated bullet bearing. Spring back is counter to last sizing action. That is, if your last sizing was inward, by quite a bit, spring back will be biased outward quite a bit(and we all know spring back varies).
Where you pre-expand with a mandrel(which is better for this than bullets) spring back is biased inward(more toward gripping). This spring back, either direction, continues over time until reaching lowest energy balance(part of the variance).

Now if you down size normally, spring back will open necks a small bit. If you follow with less expanding(than down sizing) you consume remaining down sizing energy and leave relatively less inward spring back energy out of balance. It's like halving the energy variance twice, to 1/4 that of down sizing alone.
It is possible to manage truly consistent neck tension without ever annealing, and this is a keystone action in that. This plan, including other actions, provides for much higher neck tension that is as consistent as process annealed.
There you have it, the tension advantage in neck pre-expansion.

Your telling me that freshed annealed and brass that has 10 shots on it will have the same tension if expanded to the same size each . ? Larry

 

[mikecr]

Your telling me that freshed annealed and brass that has 10 shots on it will have the same tension if expanded to the same size each . ? Larry

No, I didn't say or mean to imply that.
Freshly annealed brass offers the very least of tension(much of spring back removed), which is why it's spring back variance is very low. This is excellent provided your load likes low tension. Otherwise, you need to produce & manage higher tension.

If I were shooting an underbore and relying on high starting and peak pressure loads, I would run with higher tension than freshly annealed provides. And neck pre-expansion would help in fighting off variance with that higher tension.
But even if low tension suited my loads, and my annealing was perfect, I would still expand necks with a hardened mandrel instead of seating soft bullets. This would still drive any thickness variance outward -away from seating bullets, and reduce seating forces to rational, so that my seating depth target is easy to achieve(instead of fighting me).

I cannot think of a single down side to mandrel neck expansion. It only helps.
Now, if by "same tension" from 10 cycles, you mean tension variance in itself, this is where other actions come into play. A plan, like neck turning, better chamber fitting for lower sizing need, never, ever FL sizing necks, etc.
Unless your process annealing is perfect(lead dip), I can manage lower tension variance after 30 cycles+, without annealing, than you could at freshly annealed.

 

[savagedasher]

No, I didn't say or mean to imply that.
Freshly annealed brass offers the very least of tension(much of spring back removed), which is why it's spring back variance is very low. This is excellent provided your load likes low tension. Otherwise, you need to produce & manage higher tension.

If I were shooting an underbore and relying on high starting and peak pressure loads, I would run with higher tension than freshly annealed provides. And neck pre-expansion would help in fighting off variance with that higher tension.
But even if low tension suited my loads, and my annealing was perfect, I would still expand necks with a hardened mandrel instead of seating soft bullets. This would still drive any thickness variance outward -away from seating bullets, and reduce seating forces to rational, so that my seating depth target is easy to achieve(instead of fighting me).

I cannot think of a single down side to mandrel neck expansion. It only helps.
Now, if by "same tension" from 10 cycles, you mean tension variance in itself, this is where other actions come into play. A plan, like neck turning, better chamber fitting for lower sizing need, never, ever FL sizing necks, etc.
Unless your process annealing is perfect(lead dip), I can manage lower tension variance after 30 cycles+, without annealing, than you could at freshly annealed.

To uniform the inside of the Metal on the inside must be removed not expanded to the outside . You can't have it both ways . Larry

 

[/VH]

^I'm sensing there may be a degree of density above the neck.

 

[22BRGUY]

Wondering about Lee Collet dies and this whole process and would they move the imperfections to the outside as well? I do know they make straight ammo.

 

[savagedasher]

Wondering about Lee Collet dies and this whole process and would they move the imperfections to the outside as well? I do know they make straight ammo.

Not really they move the out side to a fixed inside diameter . They make straight cases .
Larry

 

[dmoran]

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