Neck size clarification

[UndFrm]

Hi

Fairly new to reloading, so assume I know nothing lol.

Reloading for a 6mm Dasher, and the dies I have other than the seating die are:

• Forster FL die (with expander ball)
• Redding neck size die with bushing

I have been told that the Forster FL die is over working the brass because it first contracts the neck and then expands it using the expander ball. It does have the removable expander ball. Is there a point in me getting a Redding FL sizing die with bushing? The idea is that I can remove the bushing and just do the shoulder with nothing to the neck, or if I need to size the neck, I can pop the bushing back in. OR, can I just remove the expander ball from the FL die and just do the shoulder + neck contract?

I do have a few questions regarding if and when I should be sizing the neck.
1. If my twice fired brass chambers without an issue, I am guessing that I don't need to bump the shoulders for any reason. Does this mean that I can just use my redding to size the neck and then seat the projectile? If I am not bumping the shoulder, do I even need to size the neck or can I just go straight to seating? (I am thinking not, as the neck might not adequately hold the projectile).
2. Is it recommended to get the mandrel die to expand the neck? If so, what would the steps look like? Will I be sizing the neck with the redding die (assuming I don't need to bump the shoulder), and then use the mandrel to expand? If I do need the bump the shoulder, my current Forster die also sizes the neck. Will the mandrel die be useful in this scenario?

Basically it comes down to if I should be getting the Redding FL die with bushing and/or mandrel die for neck expansion?

Thank you

 

[TheOfficeT-Rex]

I have been told that the Forster FL die is over working the brass because it first contracts the neck and then expands it using the expander ball.

It could be, or it could not be. Pop the expander ball out, then size a case and measure the neck OD across a couple spots. Then resize the same case again with the expander ball in the die, and remeasure. The difference will tell you how much it's being 'worked.'

1. If my twice fired brass chambers without an issue, I am guessing that I don't need to bump the shoulders for any reason. Does this mean that I can just use my redding to size the neck and then seat the projectile? If I am not bumping the shoulder, do I even need to size the neck or can I just go straight to seating? (I am thinking not, as the neck might not adequately hold the projectile).

Need? Not necessarily, but maybe- if you shoot in field conditions/wet weather/need every round to chamber, most people will full length resize every time.
Unless you're stripping the bolt to measure chambering force/interference, grab some form of shoulder comparator to see how the shoulder is actually moving when you fire and resize.

Yes, the neck needs to be resized after firing, with either the full length or neck only die, or it wont hold a bullet with the proper tension. If you can seat a bullet in a fired, un-resized case, there are other things you should probably investigate before continuing.

2. Is it recommended to get the mandrel die to expand the neck? If so, what would the steps look like? Will I be sizing the neck with the redding die (assuming I don't need to bump the shoulder), and then use the mandrel to expand? If I do need the bump the shoulder, my current Forster die also sizes the neck. Will the mandrel die be useful in this scenario?

The mandrel replaces the expander ball, and adds another step in either process -Resize case/neck without the expander ball in the die(sets case body dimension and squeezes the neck down), then run the brass through the expander mandrel die (open case neck back up to desired final inner dimension).
As opposed to one press step - resize case pulling press handle down (sizes body and squeezes neck) and opening neck as the press handle comes up (expander ball pulls back through the neck and sets the neck size).
Some people like them and think they help, others don't.




... That's a whole lot of words to just tell you "maybe," eh?

 

[Rocketmandb]

2. Is it recommended to get the mandrel die to expand the neck? If so, what would the steps look like? Will I be sizing the neck with the redding die (assuming I don't need to bump the shoulder), and then use the mandrel to expand? If I do need the bump the shoulder, my current Forster die also sizes the neck. Will the mandrel die be useful in this scenario?

Short answer is "yes."

Why?

An expander ball and mandrel do essentially the same thing: they both open up the neck as they pass through. The difference is:

- The expander ball is part of the sizing step and opens up the neck as the case is being backed out of the die - so it's inside and being pulled through.

- The mandrel is a separate die (so a separate step) and opens up the neck as it enters - so it is being pushed in.

If they do the same thing, why do an extra step?

First, brass is 2.5x stronger in compression than it is in tension. This means that, depending on a number of factors, you are much more likely to affect the shoulder when you're applying force pulling the expander ball back out of the case. You can elongate the case pulling it through, providing less consistency to the shoulder bump. Pushing in a mandrel is less likely to have an impact.

Second, most, though not all, expander balls are more football shaped. Mandrels tend to look more like a high-BC bullet (much more streamlined profile). This means that mandrels apply less longitudinal force to the neck per distance traveled, meaning they are less likely to deform the shoulder as they expand. Combine that to the brass being stronger in compression thing, and you get a double whammy.

Third, most, though not all, sizing dies do not have different sized expander balls for when you want to play with differing interference fit (what most people call neck tension). You can get mandrels in .0005" increments for common bullet sizes.

 

[UndFrm]

Yes, the neck needs to be resized after firing, with either the full length or neck only die, or it wont hold a bullet with the proper tension. If you can seat a bullet in a fired, un-resized case, there are other things you should probably investigate before continuing.

EDIT: Disregard this.


So....
I was able to seat the projectile without sizing the neck. The tension may not be... ideal but I wasn't able to pull the projectile out with bare hands.
I'll neck size the rest, but as you suggested, what should I be investigating now?
The brass is a twice fired, not size but annealed. The bolt closes without much resistance (just a little).

Thank you for the write up. It was really helpful.

 

[Pete B]

If you can seat a projectile, in a fired case without resizing the neck...... then you have some weird shit going on mate, or you need stronger fingers?

 

[UndFrm]

So....
I was able to seat the projectile without sizing the neck. The tension may not be... ideal but I wasn't able to pull the projectile out with bare hands.
I'll neck size the rest, but as you suggested, what should I be investigating now?
The brass is a twice fired, not size but annealed. The bolt closes without much resistance (just a little).

Thank you for the write up. It was really helpful.

Disregard this. Must be a one off. I am Infact able to pull out the projectile.

Thank you