crushing case necks when using expander mandrel to open case neck on a 338SS

[Tidesloe]

we are certainly having the same experience….

it should be no problem going from .284 to .338 many including Rich say as much.
I agree with notion these cases being too soft … I also agree with another comment about the 40° shoulder being sensitive to crushing

the suggestion of an 8mm mandrel as a second step is sound

I tried using two different lubes imperial dry lube which I've always used and Hornady's unique either prevented the problem

Hoping the longer shaft and more gradual taper in the LE Wilson mandrel will reduce or eliminate the issue.

So it's not just me. I've gone in the past from 284 to 338, with no issues but I do typically use 8mm as a 2nd step. I'm gonna have to do it again with a box of 338 Mega brass. I've not seen Wilson tapered mandrels yet, but the neck up mandrels from 21st century seem to have solved the problem for me. The neck up mandrel from one caliber to the next are nitrided so should be much better than stainless. I will sure check out Wilson and see what they've got. I do prefer LE Wilson products. Good luck

 

[MAD10]

So it's not just me. I've gone in the past from 284 to 338, with no issues but I do typically use 8mm as a 2nd step. I'm gonna have to do it again with a box of 338 Mega brass. I've not seen Wilson tapered mandrels yet, but the neck up mandrels from 21st century seem to have solved the problem for me. The neck up mandrel from one caliber to the next are nitrided so should be much better than stainless. I will sure check out Wilson and see what they've got. I do prefer LE Wilson products. Good luck

Wouldn't you know it … because of this issue I ordered a new LE Wilson expander body and .338 mandrel as apposed to Sinclair stuff. I just tried ordering a 8mm mandrel and LE Wilson doesn't make it, their mandrel sizing chart skips 8mm - bahahaha story of my life

"apparently they too think I only need two steps"

Luckily Brownell has a "tin coated" Sinclair mandrel in 8mm - accord to the description it provides less resistance than steel in a given diameter too bad they are out of .338 or I'd grab one as well

 

[Calvin45]

This is where old fashioned cartridges with less aggressive shoulders have their strengths.

I don't anneal or even use an intermediate sizing step when forming 300 win mag to .358 Norma. One pass and done. Every now and then a neck splits but I see that as weeding out the brittle necked cases to begin with

No shoulder crush.

But I agree with others that you'd probably be well served by adding an 8mm .323 expansion to this process if this is happening to you.

Sorry to hear the company you're working with don't have the right mandrel for ya. But you could always just use a boring old resizing die/expander ball combo . It's not the final product anyway, just on the way there. Any die with that .550" case body diameter and a 8mm expander ball should work for this intermediate step, obviously not to resize the whole dang case but just to run the neck through.

 

[Tidesloe]

Wouldn't you know it … because of this issue I ordered a new LE Wilson expander body and .338 mandrel as apposed to the Sinclair stuff I normally use - well I just tried ordering a 8mm mandrel and LE Wilson doesn't make it their mandrel sizing chart skips 8mm - bahahaha story of my life

"apparently they too think I only need two steps"

I was unsure of 21st century mandrels in a Sinclair die. I tried it and so far it's worked great going from 1 cal to the next in 1 step. Concentricity is good. I also have a 30 to 338 mandrel that I will soon be using. I've always used Sinclair mandrels and die body, but availability in carbide hasn't been good when I'm looking for new ones. I said I prefer LE Wilson earlier but then realized my mandrels are all Sinclair. That 21st Century neck up mandrel is not too long for SS cases.

 

[MAD10]

Gentlemen appreciate all the comments and suggestions…seems we're all of the same consensus regarding my issue and options to fix it

I'll choose one of the suggestions given

enjoy the weekend !

 

[Mike D Texas]

Just to give a visual for all viewers … the neck totally pancakes when a piece does give way and collapses …

interesting enough the actual neck OD is exactly the same as a neck that fully expanded and the shoulder didn't fail

** in this pic the .338 mandrel is hand seated in a fully expanded neck that didn't collapse…that "witness mark" is there simply to show where the mandrel stops in relation to the neck when hand seated on either a fully expanded neck or one that collapsed

again no issue going from .284 to .308 it's only when going from .308 to .338 this occurs … it's got me baffled

honestly the only thing different in each step is the mandrel … might have answered my own question right there lol


View attachment 483255

I love and have several improved cases but this is a downside to the steeper shoulder angle. 2 things that I have found that help;

1. Anneal before expanding
2. Keep the mandrel well lubed, I use imperial wax.

If I do both of these I usually don't have any problems with crushed necks.

 

[joelpend]

2 mandrels 30 cal. See the difference between a regular mandrel and a neck expanding mandrel. The expanding mandrel has a very gradual taper, hard to even see in the picture. These are K&M brand.

 

[Mike D Texas]

2 mandrels 30 cal. See the difference between a regular mandrel and a neck expanding mandrel. The expanding mandrel has a very gradual taper, hard to even see in the picture. These are K&M brand.
View attachment 483307

I have a couple of the K&M mandrels but they are limited to just a couple of options.
I have a 6mm to 6.5mm and a 6mm to 308.

 

[scpaul]

Have you tried using a vld chamfer tool before you use the expander? You might also try mika dry neck lube.

 

[Calvin45]

Maybe this is just plain stupid but how bad an idea would it be to use the cream of wheat fire forming method…for neck expansion?

Needlessly wasteful of primers no doubt but besides that is there a reason the op couldn't just fireform expand the necks in the chamber, run them through the sizing die after just to be sure it's all uniform, and get loading?

 

[Tiny Tim]

Maybe this is just plain stupid but how bad an idea would it be to use the cream of wheat fire forming method…for neck expansion?

Needlessly wasteful of primers no doubt but besides that is there a reason the op couldn't just fireform expand the necks in the chamber, run them through the sizing die after just to be sure it's all uniform, and get loading?

Perhaps some cheap primers. I see Chedite (?) Primers here occasionally for less than name brands

 

[scpaul]

I don't think that the Cream of Wheat method will expand the neck. I use it to remove some case taper and to form the shoulder.

 

[Calvin45]

I don't think that the Cream of Wheat method will expand the neck. I use it to remove some case taper and to form the shoulder.

Why wouldn't it? Just not enough pressure to force it open? I just don't see why it would be able to make a shoulder move, or blow out body taper, but not expand a neck. What am I missing here? (I really do know nothing about this, just spitballing here)

 

[scpaul]

To build pressure in the case, I pack the case up to the neck with toilet paper over the powder to build pressure. The paper is gone by the time that the pressure would build enough to expand the neck.