case turning question

[nra-for-life]

hi all, i am struggling to get a consistant runout my cases and my neck tension is not consistent, i believe this is also possible effecting the seating depth on my bullets as well... I am really considering turning cases. after thinking about the concept of this i am curious how case turning works with tapered case necks as the taper in the neck would cause the turning to create a thinner neck as it went back toward the shoulder. to illustrate my question i drew some pretty pictures. there must be something here that i don't understand. how is a case trimmed on a tapered neck without creating a thin area? thanks

 

[Cigarcop]

When you expand the cases for trimming with an expander mandrel the cases will be straight taking any taper out for turning.

 

[nra-for-life]

okay that is kind of what i was thinking... so if the mandrel expands the neck take the taper out, then is the taper put back in with a die afterwards or is the taper just left out of the case neck for good??

in examining my forster bump neck sizing die, the neck bushings would not reform the taper as they are the same size on both ends:

are there some dies out there that will re-form the taper??? is the chamber of the gun isually shaped for this said taper or is it typically shaped with a straight wall?? thank you.

 

[Codeman]

What cases are you reloading that have a tapered neck?

 

[nra-for-life]

22-250

 

[K22]

Great question, I don't turn necks but often wondered about this too.

I shoot a lot of 22 250. I get very little run out by full length sizing my brass but only pushing the shoulder back slightly. I set up the die with a Wilson Case Gage so it sizes between the upper and lower steps. For my rifle, it means having the die just touching the shell holder. I get good case life using this process but my cases are used in the same rifle.

 

[markr]

The neck (smaller portion that holds the bullet) should not be tapered! Run your case over the expander mandrel, turn it to whatever size you need, champher, load and shoot. If you are perceiving a taper in the neck, it is not supposed to be there and your fired brass will show that when it's all said and done.

 

[jsn]

The SAAMI spec for 22-250 does show a .002 taper from the junction of the shoulder to the trimmed edge. Is this what you're seeing?

In fact, a number of cartridges do show from .001 to .002. A number don't as well.


http://www.saami.org/specifications_and_information/publications/download/206.pdf

 

[jsn]

I'm assuming that taper in the drawing still leaves an internal dimension that is for a non-tapered .224 bullet. It doesn't show in the drawing, but what else could it be?

 

[nra-for-life]

The SAAMI spec for 22-250 does show a .002 taper from the junction of the shoulder to the trimmed edge. Is this what you're seeing?

yes, and i'm able to verify it by measuring also.

 

[BoydAllen]

All unturned necks are tapered. Section a case, and think about how they are made. If you are resizing fired necks prior to expanding for turning, you need to use a one piece die, because bushing dies do not quite get to the shoulder. The thickness of the turned neck is determined by the distance between the cutter and turning mandrel. Its consistency is determined by the fit of the neck on the mandrel, which does not have to be as tight as some believe, and technique. Your drawing shows and incorrect stopping point at the base of the neck, and does not show the result of a cutter leading edge chamfer, sometimes referred to as the cutter angle. Your cut should extend into the shoulder, but only to a very shallow depth.

 

[Catfish]

If you are workinf with a factory chamber I would not recomand turning the necks. Reason is that they are so large that you will increase case neck work and shorten the case life a bunch. As for bullet hold, my guess is that the your case neck thickness varies. I hope you are not useing a neck expander ball if you are useing bushing dies because they only can cause trouble if you are useing the correct bushing die.

 

[markr]

I'm assuming that taper in the drawing still leaves an internal dimension that is for a non-tapered .224 bullet. It doesn't show in the drawing, but what else could it be?

Using current tooling, it would be rather difficult to turn that .002 taper onto he outside of the neck while leving the inside of the neck wall straight, would it not? Do a chamber cast of the 22-250 chamber and see if that taper is present.
Mark

 

[Elkbane]

NRA,
Ignore the drawing. Turn as BoydAllen reccomends, uniforming the neck walls and just nipping into the shoulder. Your die will determine whether a taper is established on the finished caseneck, whether your chamber has a tapered neck or not. Once your neck walls are uniform, you'll be able to tell whether the die has a tapered neck (by measuring a uniformed sized case) and whether your chamber has a tapered neck (by measuring a fired case). But at least your case necks will be uniform, which should reduce runout.

My guess is that your die doesn't have a tapered neck - it would be impossible to design an expander ball that would produce a taper on the neck.......(it's a fixed diameter and when operated in a linear fashion, will produce only one diameter inside hole)..
Elkbane