Expander mandrel consistency?

[jvshiver]

I’ve seen a lot debate in different places about the use of expander dies and mandrel for consistent neck tension, and affecting concentricy. I have used an expander mandrel some and can definitely see a huge difference in my neck tension consistency, but I do not have a gauge to measure concentricy. What’s your findings

 

[mgunderson]

Might want to give everyone a little background on what game we are discussing and the caliber. It helps to keep the discussion from getting off track.

 

[jvshiver]

6BRA benchrest rifle

 

[Fuj]

A good anneal is key to keeping numbers close.

 

[Mark611]

Do you turn your necks at all? I turn mine just enough to remove the hi spots just enough to uniform them, then when prepping for a load I neck size my necks with a LEE collet die, I get a runout of 1k or less, if you don't have a concentricity gage, I would buy 1 if accuracy is important to you? JMO, brass prep is very important for good accuracy!

 

[jvshiver]

Do you turn your necks at all? I turn mine just enough to remove the hi spots just enough to uniform them, then when prepping for a load I neck size my necks with a LEE collet die, I get a runout of 1k or less, if you don't have a concentricity gage, I would buy 1 if accuracy is important to you? JMO, brass prep is very important for good accuracy!

Yes my chamber is a no turn neck but I just do skim the high spots as well, i anneal after every firing, and I size with Harrels full length die and .004 under bushing

 

[mgunderson]

Anytime the brass changes size after firing you have the potential. Factory expander ball removal was a big concentricity factor for me. Then the neck thickness variations became more obvious. With a partial neck turning it was smaller and more stable...... then I sold that darn concentricity tool and focus more on shooting more and trying to listen to the target. Not sure any of it helped my scores, but it did ease the voices in my head.

I expect benchrest with a potential jammed bullet in the lands to be a little different. The precision requirements are different.

Are you having an issue that you think is related to concentricity? I have learned more from having two rifles. Much easier to isolate issues when it happens on both rifles or just one.

 

[6.5 forever]

A good anneal is key to keeping numbers close.

I anneal and use a carbide mandrel every firing. Make sure you keep the mandrel clean.

 

[mikecr]

I have used an expander mandrel some and can definitely see a huge difference in my neck tension consistency,

How do you 'see' neck tension?

Runout accumulates from ALL sizing, FL of the case, and from seated bullets.
A mandrel helps with seating bullets straighter, and mitigates the puling of necks off-center with a button.
I've been using mandrels for pre-seating around 40yrs now. Never pretended this was for adjusting tension.

 

[rijndael]

How do you 'see' neck tension?

AMP Press?

 

[L.Sherm]

If you turn necks i see no reason to use an expanding mandrel.

 

[rijndael]

If you turn necks i see no reason to use an expanding mandrel.

If the mouth gets dinged up on the side of the action or bouncing off the ground.

Not all of us single feed and manually extract.

 

[L.Sherm]

If the mouth gets dinged up on the side of the action or bouncing off the ground.

Not all of us single feed and manually extract.

I dont either

 

[rijndael]

Great. Then you know it's pretty common for mouths to get out of round. Mandrels are an easy fix for that issue.

 

[Ned Ludd]

Not sure exactly what your question is here, but in a nutshell, the main difference between an expander ball and a mandrel is that the expander ball is pulled back through the neck after it has been sized with a bushing, whereas a mandrel is pushed into the neck from the outside. The pulling out of the expander ball is generally believe to be cause of runout for those that have experienced it. Having said that, both an expander ball and a mandrel can be set up [properly] to produce necks that have minimal runout. IMO - properly setting up an typical mandrel die such as the ones obtained from 21st Century or Sinclair requires very little knowledge or experience. They work very well straight out of the box. An expander ball can be a slightly different story; sometimes more work such as slight re-sizing of the expander ball may be necessary. Regardless, the ball must pull straight back through the neck or runout may be induced.

In my hands, the use of a mandrel to set final neck tension has resulted in a slight but noticeable improvement in the consistency of neck tension. I also primarily run no-turn neck chambers and the use of a mandrel has helped improve neck tension consistency in cases that have not been neck-turned. In fairness, I remove the expander ball from every die as soon as I get it, so I have never had any issues with runout. Along that line, I use mandrel die bodies from 21st Century and Sinclair and have never had any issues with runout being induced by the use of a mandrel. With a properly machined die body and mandrel, runout shouldn't be an issue, unless something something is wrong elsewhere in the process/press setup.

 

[mikecr]

AMP Press?

That's seating force/friction. K&M, 21st, and RSI did the same without the motor drive.
With friction normalized, and NOT FL sizing necks, a tension outlier can show up with this.
Of course by then, it's too late to do anything about it but separate the round.

Amp would have been wiser to instrument a mandrel die and motorize a purpose built seating press -for this measure. It would then be a pre-seating operation, providing opportunity for ACTUAL tension adjustment (length of sizing) on the side, to match each round pre-seating force.
With that you wouldn't be doing all this with soft bullets, but a low friction carbide mandrel.

 

[1K Luver]

This is how I do it.

Amazon.com

I also have a neck thickness gauge listed for sale elsewhere in the forum if you need that.

 

[Charlie-NY]

I have been using Redding Type S FL bushing dies for quite some time now. While I don't have an issue with them I did notice that some bullets take more force to seat than others. I decided to try the Centry 21 mandrels to see if it made any difference. I also use their moly/ceramic balls to lubricate the case neck. There has been a noticeable improvement in seating consistency. There is a more consistent force needed to seat the bullets and I measure less deviation in CBTO after seating.

After running the mandrel in & out, I use a Q-tip to run a circle around the inside of each neck. It does remove a small amount of moly powder. What do other mandrel users do?

 

[Mark611]

What I do is this, I use the Sinclair mandrels with the body for the mandrels/or die, I have the carbide turning mandrel and the expander mandrel, for the calibers I reload for, I turn my necks just to remove the hi spots, that's after I trim to length, and usually with new brass 100% of the time, case prep! then size them with the LEE collet die, load and shoot them to fire form the brass, after firing the brass there is almost zero on the runout! so your sizing matters for the neck and body JMO

 

[jvshiver]

AMP Press?

Not the amp press but I think it’s K&M or either century 21 with the seating pressure gauge