When/Why use an Expander die?

[TheGerman]

When or why would you use an expander die? I see them online but have never seen/read of why you would use it and what it achieves (obviously it expands the case mouth only, to the diameter of the mandrel) but what would indicate the need to use one, then benefit of using it, and is it specific to rifle only, or pistol only, etc?

Thanks

 

[thrusty]

To expand the case mouth so it doesn't shave off any of the bullet....ie: when using cast bullets in handguns.

 

[308boltgun]

For bottleneck cases (i.e. rifle) this is done with the sizing / de-priming die.
A normal sizing die squeezes down the outside diameter of the neck. Since there is variation of the outside wall thickness, the diameter of the INSIDE is what is important for the bullet to fit and stay tight. The expander button opens it back up to the right INSIDE diameter for the bullet to fit.

For straight wall cases (i.e. most pistols)
There is a separate die that opens the mouth up a little bit so the bullet can go in without shaving off the sides. It mouth then gets pushed back in by either the seating die or the crimp die, depending on what brand / variation of die set you have. Not all reloaders use the expander die. If you are loading jacketed bullets, it may not be needed in some cases.

 

[ksthomas]

German,

Very necessary for handgun rounds, as the previous posters have indicated, and are a standard die in most three-die sets. The expanding/belling die also gets used as a powder delivery point in most progressive press systems, but I suspect that this isn't what you're asking about. You're probably talking about the specific expander dies sold by Sinclair and others?

I recommend the use of these expander dies (mandrel type) for use with new brass, just to assure that the case mouths are perfectly round after shipping, and to even out the neck tension, should there be any variation. Specialized dies, and not something I use on every reloading run, but they're a very useful tool when you're doing these tasks. They are also, hands down, the best way to go when necking cases up for a wildcat, or simply forming cases into another caliber. From 223 into 6x45, 30-06 into 338-06, whatever, these dies are the easiest means to make the conversion. If you're doing anything like this, yeah, you need them.

 

[Juma]

Use a Lyman M Die when reloading Barnes projectiles especially in 223 and 223WSSm. Brilliant tool and seats those long copper shafts like butter.

 

[bigedp51]

The expander die is normally used for neck turning or expanding the neck in a separate operation. Many feel that expanding the neck this way reduces runout because:

1. You are expanding the neck with the case sitting on its base with less chance of the case being tilted in the shell holder.
2. The mandrel floats and self centers itself in the die reducing the chance of pulling the neck off center as can happen in a normal resizing die.

Expander Mandrels and Neck Tension within AccurateShooter.com

Complete Precision Case Prep within AccurateShooter.com

Neck-Turning Basics within AccurateShooter.com

 

[peaceatwar]

I use a Sinclair neck expander on new hornady brass to ensure uniform neck tension without re-sizing. I find the factory necks to be very tight.

 

[rjacobs]

I run one on my Dillon 1050 brass prep tool head since the Dillon trim dies have tight necks since they are cut with a reamer designed for a full length size die. Need something to open up the neck and set neck tension since there is no expander ball in the trim die. I run the 21st century unit and so far its been awesome through about 10k pieces of 5.56 brass.

 

[milo 2.0]

I use a Sinclair neck expander on new hornady brass to ensure uniform neck tension without re-sizing. I find the factory necks to be very tight.

PAW may be right on new Hornady brass, but for most instances, if you run a case into an expander die, you've essentially just seated and pulled a bullet, so to me, putting original neck tension back on the case is in order.

All pistol die sets come with an expander die, so you must seek out a rifle expander die.
Expander dies are great for straightening case mouths, and are slicker than snot for necking up to a diff caliber.

 

[bigedp51]

PAW may be right on new Hornady brass, but for most instances, if you run a case into an expander die, you've essentially just seated and pulled a bullet, so to me, putting original neck tension back on the case is in order.

All pistol die sets come with an expander die, so you must seek out a rifle expander die.
Expander dies are great for straightening case mouths, and are slicker than snot for necking up to a diff caliber.

With my Sinclair expander die it has two different size mandrels that can be ordered for each caliber, in .224 caliber the mandrel sizes are .223 and .222. The .223 mandrel is for sizing the neck for neck turning and the .222 is the standard expander mandrel. Expanding to .002 under bullet diameter is more than enough neck tension for reloading and most expander buttons in the die itself are closer to .001 under bullet diameter.

SINCLAIR GENERATION II EXPANDER DIES | Sinclair Intl

SINCLAIR NECK TURNING MANDREL | Sinclair Intl

Also your neck tension is governed by neck thickness when sized and the diameter of the expander and brass springback. When your expander is too small your case trimming can cause problems after sizing and the neck will bind on the trimmer pilot and end up galling the inside of the case neck.

At Accurateshooter.com many of the compeditive shooters just run new brass through a expander die and shoot and no one complains about loose necks. Some shooters have very little neck tension and jam allowing the bullet to be seated by the lands in the throat. At the other end of the spectrum AR15 shooters decrease the size of the expander button to increase neck tension instead of crimping their bullets. Bottom line, expander dies have many uses and neck tension is decided by the individual shooters.

 

[bigedp51]

And now that Lyman's type "M" die patent has expired everyone is jumping on the band wagon.

Redding pistol die below with the type "M" expander

Below, A. expand, B. bullet step, C. flair or bell case mouth.

 

[Jager66]

I use Sinclair expander mandrels on my brass.
I have found that concentrity benefits from this operation.
I use to have quite bad co-ax results with the original expander rod, so I've got rid of it and started with mandrels.
But it could be just hype........

Inviato dal mio GS 1150

 

[Assault116]

Also useful for necking brass up to a bigger size, for instance 243 win to 260 brass ect. That's one of my primary uses for them, it's a bit nicer to be able to see everything and reduces the chances of ending up off center and screwing up the case mouth.

 

[jpistolero02]

I use a Sinclair expander after full length sizing each time. Maybe I am doing it all wrong, but it seems to work for me.

 

[mudpig]

+ 1 on turning necks and necking up to larger caliber

 

[redbullitt]

I use one for cast bullets all the time in 30 cal, other wise the driving bands and lube can easily get shaved.

 

[Layton]

I use one for new brass only to give me .002" neck tension since as mentioned earlier new brass is typically too tight. Redding f/l bushing dies after that to get back to .002" neck tension after firing.

L

 

[OKbow87]

I use them for several operations. The most important is creating a false shoulder for proper headspace when firing new brass for the first time. I use a mandrel on size up, so .277 if I'm loading .264 caliber. Then neck down part of the neck at a time until my bolt will just close with some resistance. It mitigates lots of problems out of the gate.

The second is for neck turning. But there are lots of other things it can be used for. Rounding out dented necks, setting neck tension to .002 if you use standard full length dies instead of bushing, etc.

A great tool any reloader should have.

 

[Vettepilot]

I realize this is an old thread, but my question seems to fit here, so here goes...

I have quite a number of 30 caliber, and some .223 and .243 flat base jacketed bullets to load up. As you know, flat base bullets can be hard to get started in the seating operation. NOE sells two step expander mandrels for seating bullets cast in their molds. How would it be to use those for seating flat base jacketed bullets??

Let's take 30 cal for example. Get an expander mandrel sized .306/.308. Then set it up so that the top say, .020" of the neck is sized to .308, allowing for an easy start when seating flat base jacketed bullets? Any problems with this idea?

Thanks!
Vettepilot

 

[b2lee]

I load a lot of .223 flat base bullets....by a lot...I mean somewhere in the neighborhood of about 10,000 a year. I make these bullets from spent 22lr brass and a lead mold that makes cylinders. I make a nice 60gr open tip that generally has a big C for CCI on the base. Very cheap and fun plinking ammo.

What I do is....I use my full length sizing die without the expander ball. Then I use a mandrel to open up the neck to about 2 thou of neck tension. I don't 'flare' the case mouth like you would do on a pistol....With just 2 thou of neck tension the flat base bullets go in very smooth and easy. If they are for accuracy...I don't crimp....if they are for WW3 or zombie ammo..they get a nice crimp.

I don't shoot flat base in my 308 but I do in my 8mm Mauser and I do the same there.

So yea....get a mandrel about 2 thou less than the bullet....maybe 3 thou...due to spring back....no need for a 'two step'.

 

[pmclaine]

Wouldn't be interested in an expander die unless shooting flat base bullets in rifle.

I load on a Dillon so for pistol the powder die expands the neck to seat the flat base projo and in the last station my "crimp" returns the case to straight wall or just kisses the projo sealed.

Rifle I use a mandrel die to even out neck tension and boat tail bullets slide in like a tube steak in GAGA.

 

[pmclaine]

Man necro thread, just noticed.

@TheGerman has probably bought an ammo manufacturer by now and moved on.

 

[b2lee]

Man necro thread, just noticed.

@TheGerman has probably bought an ammo manufacturer by now and moved on.

yep....necro...but hey...better than starting a new thread and getting jumped on by people telling you to use the search function.

If he did buy an ammo manufacturer...GET TO WORK!!!! Only about 67 billion rounds behind...geez...

 

[Gustav7]

I realize this is an old thread, but my question seems to fit here, so here goes...

I have quite a number of 30 caliber, and some .223 and .243 flat base jacketed bullets to load up. As you know, flat base bullets can be hard to get started in the seating operation. NOE sells two step expander mandrels for seating bullets cast in their molds. How would it be to use those for seating flat base jacketed bullets??

Let's take 30 cal for example. Get an expander mandrel sized .306/.308. Then set it up so that the top say, .020" of the neck is sized to .308, allowing for an easy start when seating flat base jacketed bullets? Any problems with this idea?

Thanks!
Vettepilot

I feel like thats a little more trouble than you need to make it.

I've used 1 and 2 thou neck tension and either work fine. Run another turn or two on your chamfer, and hold the bullet as you run the press up. Once the bullet tip is inside the start of the seating die, it shouldn't give you trouble.

 

[Vettepilot]

Problem is, I've got rather large hands and fingers for holding the little guys in place until they get a start. Plus, 50 plus years of physical abuse of my fingers in my various work activities has made my fingers quite insensitive, and that makes holding small items precisely difficult. (Example: I can pick up hot coals that pop out of a fire and toss them back in without a thought...)

Vettepilot

 

[Gustav7]

Problem is, I've got rather large hands and fingers for holding the little guys in place until they get a start. Plus, 50 plus years of physical abuse of my fingers in my various work activities has made my fingers quite insensitive, and that makes holding small items precisely difficult. (Example: I can pick up hot coals that pop out of a fire and toss them back in without a thought...)

Vettepilot

Yaaaa, I know exactly what you mean. My old man is a mechanic of 40yrs and a farmer, he’s the same way.

In that case I would try to just slightly bell the case mouth like you’re taking about. I would make sure you’re just belling the mouth and not actual expanding a portion of it completely. What comes to mind would be using a 6.5 or 30 cal mandrel, and just barely pushing the rounded off tip in to where it just bells the mouth a tad. I’d run a sized case up in the press, then screw down the mandrel die until it touches, then screw in another 1/4 turn or so. Basically just recreating the belling you would do on a pistol case.
I’m sure they make something specific for this but I already have Mandrels so that’s why I suggested that.

 

[memilanuk]

I use a Forster micrometer seating die and it reduces the flare when seating the bullet.

How does it do that?

 

[MarinePMI]

How does it do that?

A seating die is basically cut with a chamber reamer. So when seating a bullet, the die sizes the neck (irons it flat actually) back to where it should be (dimensionally). Also, if the die has a crimp (many do), then it has a taper, and screwing the seater die down far enough to just not crimp, will accomplish the same thing.

 

[Campguy308]

Back when i used redding S dies, if there was a case mouth that was dented, the die would never iron that out.

I think lots of people remove the expander ball, use a slightly smaller bushing than necessary, then run the mandrel in to set tension and iron out any irregularities.

Personally I prefer a lee collet die for neck sizing, along with a Redding body die.

 

[memilanuk]

A seating die is basically cut with a chamber reamer. So when seating a bullet, the die sizes the neck (irons it flat actually) back to where it should be (dimensionally). Also, if the die has a crimp (many do), then it has a taper, and screwing the seater die down far enough to just not crimp, will accomplish the same thing.

I'm well aware most micrometer seating dies have a sleeve... which usually still has some clearance to allow for different neck wall thicknesses, the little bulge in necks from using bushing sizers, etc.

And I've never, ever, heard of a micrometer seating die that does crimping, taper or roll. Usually that is only a 'feature' of lower end dies.

 

[memilanuk]

ack when i used redding S dies, if there was a case mouth that was dented, the die would never iron that out.

The only way that the dent wouldn't iron out is if they removed the expander.

I'll admit, the stock expander plug kinda sucks. Replacing it with the Redding carbide ball fixes pretty much all the ills attributed to expanders in general. Using a bushing sized so the ball just 'kisses' the neck on the way out typically leaves you with a perfect two thou neck tension. If you wanted more or less,things got interesting.