I'm Confused............

[Twud]

I don't understand how a neck sizing die works. I'm working under the assumption that upon firing the case neck expands under the pressure applied to it by the charge. If this is so why is there and expander button? It would seem that the button would expand the brass, then the die would reduce it and then the button would expand it again. There is obviously some flaw in my reasoning.
I'd really appreciate an answer from you guys that know this stuff.
Mark

 

[tightneck]

Upon firing, the case expands to the walls of the chamber and then springs back a little. In a standard die,FL or Neck) the expander ball,I hate even saying these two words) doesn't touch the neck until the case is being removed from the die. The neck in the die is made very tight, and the expander ball brings the neck back up to a uniform dimension so as to give the necks the same amount of tension on the bullet. This procedure overworks the brass and stretches it, meaning more trimming, and also creates excessive runout. Moral of this story: USE BUSHING DIES AND THROW THE EXPANDER BALL IN THE TRASH CAN. Quality brass,uniform) and bushings make it so you can have uniform and controlled neck tension.

 

[amamnn]

the expander ball,I hate even saying these two words) doesn't touch the neck until the case is being removed from the die.

au contraire!!!

The expander ball works the neck on both directions of the ram stroke. This has given many people the idea that it overworks the brass, and pulls the neck out of alignment with the case body. In many cases, using standard,cheaper) FL dies, this is true. However, Forster's benchrest dies have a different arrangement of expander to work with the neck sizing portion of the FL die which actually aids concentricity of neck and body. Others may have copied this design by now, I don't know.

Neck dies, which are falling out of favor with many benchrest and other precision shooters, resize only the outer neck diameter of the case, and so do nothing to set shoulders, or ensure body/neck concentricity. More shooters are coming to understand the importance of these two variables and their control does much to improve accuracy.

Certainly, when we are discussing accuracy as applied to today's factory rifles, neck sizing dies are largely the best way to go. IMHO, Lee makes the best one on the market. Using bushing dies to load ammo for 99% of factory rifles is like putting mag wheels on a Ford escort. Looks neat but does nothing for performance and makes a lot of onlookers chuckle. Factory chambers are much too loose to bother with running down the OD of your case neck, and 99% of reloaders don't ream the insides of their necks, so what good are you doing? Well, you're helping Redding and Forster to meet the payroll................

 

[tightneck]

the expander ball,I hate even saying these two words) doesn't touch the neck until the case is being removed from the die.

au contraire!!!

The expander ball works the neck on both directions of the ram stroke. This has given many people the idea that it overworks the brass, and pulls the neck out of alignment with the case body. In many cases, using standard,cheaper) FL dies, this is true. However, Forster's benchrest dies have a different arrangement of expander to work with the neck sizing portion of the FL die which actually aids concentricity of neck and body. Others may have copied this design by now, I don't know.

Neck dies, which are falling out of favor with many benchrest and other precision shooters, resize only the outer neck diameter of the case, and so do nothing to set shoulders, or ensure body/neck concentricity. More shooters are coming to understand the importance of these two variables and their control does much to improve accuracy.

Certainly, when we are discussing accuracy as applied to today's factory rifles, neck sizing dies are largely the best way to go. IMHO, Lee makes the best one on the market. Using bushing dies to load ammo for 99% of factory rifles is like putting mag wheels on a Ford escort. Looks neat but does nothing for performance and makes a lot of onlookers chuckle. Factory chambers are much too loose to bother with running down the OD of your case neck, and 99% of reloaders don't ream the insides of their necks, so what good are you doing? Well, you're helping Redding and Forster to meet the payroll................

Let's take a SAAMI 30-06 chamber for example. The neck diameter is in the neiborhood of .345, so a fired case will exit the chamber around .344. An expander ball would have to be .314,give or take depending on the brand and lot of brass) in order to touch the case neck upon entering the die. The case when it leaves the die would never hold a bullet. Expander balls usually measure a few thousnaths under bullet diameter so that they will hold the bullet firmly, and therefore cannot work the caseneck before it has been sized by the die. You may be correct that the bushing dies aren't the best solution for factory rifles, but being that this is an accuracy forum, I am almost always refering to custom rifles and chambers. Honestly, its been so long that I reloaded for a factory rifle that I don't give expander balls a second thought anymore.

 

[amamnn]

Ihave the expander out of a couple of dies and just to double check I tried to pass it through the neck of a new case--it did not go in without being forced.

 

[amamnn]

funny you should mention that--after posting---and reading what was posted by others that flys in the face of 50 years loading experience---I went in and did just that with some fired brass that I've had for a while--same thing: the ball did not pass .223--6mm---308 all the same I suggest you try it yourself--brass rebound does work both ways. I have not tried this with a case hot from the barrel yet-----

 

[tightneck]

funny you should mention that--after posting---and reading what was posted by others that flys in the face of 50 years loading experience---I went in and did just that with some fired brass that I've had for a while--same thing: the ball did not pass .223--6mm---308 all the same I suggest you try it yourself--brass rebound does work both ways. I have not tried this with a case hot from the barrel yet-----

I don't see winning this argument with you because you have so much "experience" but just for kicks I just took two 30-06 cases over a redding 30 cal expander ball and what do you know, NO RESISTANCE. One case was fired about 15 years ago and the other within the last year.

 

[rstreich]

Twud, the expander ball is there because non-bushing dies use the expander ball to expand the neck to the finish size. The bit about overworking the brass has nothing to do with the expander ball. The problem is that the neck sizing portion of the die typically sizes the neck down much smaller than necessary.

For example, I have a .204 Ruger non-bushing sizing die that I took the expander ball out of just to see how far it was sizing down the neck. When I ran a case through it, it came out around .006" too tight. So it was relying on the expander ball to open it back up that .006". Considering that in a typical tight-neck chambered rifle you're only reducing the neck between .004" to .006",depending on your neck tension), that extra .006" means that you're working your neck twice as much as you need to. Even if it's a factory chamber with a looser neck that's still .006" of sizing that you didn't need.

tightneck is right: If you're using a bushing die, you don't want to use the expander ball as it just gets in your way. The size of the bushing controls your neck tension.

BTW, don't let anyone distract you with talk of inside neck reaming. It does nothing to aid concentricity.

 

[thane]

Twud
If you are using good brass with even wall thickness or you are turning your necks then you won't require using an expander ball.
Measure neck wall thickness on three points around and if the thickness varies more than 0.0005", you may want to consider getting better brass or using an expander ball. Ofcourse this all depends on your expectations.
Listen to what everyone is telling you but in the end you will learn what works best for you.
Thane

 

[beartrack]

Isn't this becoming overly complicated? Measure the inside diameter of the case mouth on fired case. Measure the expander ball. Which is bigger?