mandrel for case necks...can somebody please explain

[justinp61]

Please pardon my ignorance, one camp says bushings push any variance in and the other says mandrels push it out, okay I got that.
If my bushings push the inconsistency to the inside doesn't the bullet push it back out, like a mandrel?

It appears that unless you have good brass or neck turn its six of one and a half dozen of the other.

 

[FEENIX]

its fairly easy to follow the money. Youtube pays for these videos. They get the money from the manufacturer. As the consumer, we need to decifer through the BS

No one is forcing anyone to buy anything or follow their process(es); people got a piece of free information. I, for one, am thankful for this type of information and appreciate video poster time and effort in sharing it. I do not care if posters are self-funded or sponsored.

 

[UncleDano]

this is pretty new and I might be a little slow.
I understand the theory of turning necks, neck sizing without full length suze and full length plus using a neck bushing to resize a neck to customize neck tension on a bullet.
However, I hear talk about using a mandrel that pushes into the neck. I don't understand why one would want to do that if you can resize the neck from the outside.
Can somebody walk me through this? I've reloaded my own ammo for 25 years, but this seems odd to me.

Shawn
When we pull a expander Ball back through the neck to set the final neck neck diameter we stretch the neck and introduce more runout.
We have learned that a Mandrel pushed into the neck does not stretch the neck and introduces much less runout.
The reason we use a Mandrel to expand the neck instead of relying on the neck bushing is because brass resists the last direction we move it in. Plus the Mandrel pushes the imperfections to the outside of the neck causing more consistent neck tension.

So are you saying that pushing an expanded ball into a case mouth (like a mandrel) does not introduce runout, but pulling it out of the case mouth does produce runout?
I wonder how much distortion is produced buy a out of tolerance or worn shell holder?

 

[milboltnut]

A worn out shell holder? The casing floats and even a new shell holder has play in it, it's suppose to. The case finds center in the die.

 

[QuietTexan]

Please pardon my ignorance, one camp says bushings push any variance in and the other says mandrels push it out, okay I got that.
If my bushings push the inconsistency to the inside doesn't the bullet push it back out, like a mandrel?

It appears that unless you have good brass or neck turn its six of one and a half dozen of the other.

You're entirely correct that bullets can expand the neck. I use bushing dies and mandrels to manage seating force because I want to see consistency there, and the level of pressure that comes with expanding the neck while seating a bullet will obscure what I'm looking for.

I fully agree with the last part, this mandrel concept is pretty far down the road of assuming a bunch of other things, including the rifle, are up to the level of precision differences in sizing methods is even apparent. There's no need to use a Prometheus to load charge weights for mixed headstamp cases because case volume varies so much that the improvement resulting from increased charge precision will never show up on a target. There's similar logic in sizing process discussions, a lot of the time it doesn't ultimately matter.

So are you saying that pushing an expanded ball into a case mouth (like a mandrel) does not introduce runout, but pulling it out of the case mouth does produce runout?
I wonder how much distortion is produced buy a out of tolerance or worn shell holder?

The mandrel pushes down on the case neck, so the way it's applying the compression load to the roughly triangular shoulders basically converts the compression load on the shoulders to tension in the circular body. When you pull out against the neck it's the opposite, the tension is on the shoulders and if they give even slightly then you induce runout. If you stand on top of a triangle it's strong - if you stand in the middle of one side it's not.

 

[Dragoon300]

I have found that when pulling an expander ball out of a case, especially if it is not lubed properly and squeaks, there will be be noticeable runout.

Using a die with an expander ball accomplishes the same thing as using a die without an expander ball, and then using a mandrel. Both expand the neck after the neck has been reduced.

Only the direction of force is different, and as was stated above, the force pushed into the neck that is supported by the shoulder is less likely to bend or change the shoulder under compression, as opposed to pulling on the neck and stretching the shoulder.

On bushing dies when some select a bushing to establish the desired neck tension, and do not use an expander ball, the uneven wall thickness (if there is any) is pushed to the inside, which can cause runout when the bullet is seated.

I have found using a bushing that reduces the neck .002 to .003 smaller than the desired ID, then using a mandrel to expand the neck to the desired ID produces more consistent neck tension without distortion.

 

[milboltnut]

sounds like the ID as well can help runout, whether a bushing or mandrel is used. After I neck turn the neck thickness is the same after I mandrel size.

 

[Dragoon300]

sounds like the IDOD turning machine can solve any runout, whether a bushing or mandrel is used. After I neck turn the neck thickness is the same after I mandrel size.

No, not necessarily. ID OD turning if done correctly fixes the Wall thickness issues, not runout. If you do anything to distort the neck or cock the projectile in the reloading process you will still get runout. Then there is neck tension consistency to consider. Bushing, expander ball, mandrel? Take your pick.

 

[Csbc4fun]

I'm a bit of a perfectionist, just NOT to the point of a benchrest artist. I like accurate rifles, but most of mine are of the AR configuration.
I would like to shoot accurately out to 1/2 mile under 1moa.
To answer your question about the KIND of shooting, I used to shoot game, but my broken down body won't allow me to chase elk where they live. Deer us still an option, but coyotes and prairie dogs still remain my preferred quarry.
I shoot paper to test my handloads for accuracy

I use a mandrel as a last step finishing tool to ensure my necks are uniform after sizing and cleaning. I thought that my tumbler s pin cleaning process may be degrading the neck condition. Every once in a while I would feel more tension when seating a bullet. After using the mandrel that all went away and all my bullet seating feels the same. I trim every time and the brass stopped growing with mandrel use. Now I trim very little shavings off each case.

 

[milboltnut]

No, not necessarily. ID OD turning if done correctly fixes the Wall thickness issues, not runout. If you do anything to distort the neck or cock the projectile in the reloading process you will still get runout. Then there is neck tension consistency to consider. Bushing, expander ball, mandrel? Take your pick.

I know that mandrels give me consistent neck tension and consistent accuracy better than I used to get. Runout? I used Bananza/Forster BR seater, but see Redding standard seaters do better. My Redding body sizer and Lee Collet neck die and Redding seater beats the first with .0005-.001 bullet runout

 

[CBH Australia]

mandrel are supposed to create less runout verses bushings. Debatable whether a little runout effects accuracy, and if it's worth it using mandrels over bushing. Choice is yours. Buy both and see. Easy explanation ?

Summed up in one reply.

How much does runout matter?
Serious question.
Surely having the chamber cut square and concentric matters
And a good crown on the end of the barrel.
Is runout corrected by 20" of travel in a barrel?
A damaged crown will surely send a bullet off centre

 

[motrapper]

Following

 

[milboltnut]

And yet here you are giving your opinion on what the best way to do something might be. Interesting.

he's way too detailed... be honest, he has his way and I would say alot of it is unnecessary ! LOL Measuring bearing surface on bullets ? LOL

 

[FEENIX]

And yet here you are giving your opinion on what the best way to do something might be. Interesting.

"My" list just got longer!