Expander dies. Who’s using them?

[Benchguy]

I’ve been reading and listening about using neck sizing dies. Took some measurements of my current Hornady 22-250 sizing die. The expander ball in that die measures .221. Fired case measures .222. After running it through the die, it measures .218, giving me a .006 neck tension on the 40Gr .224 V-Max bullet.

My “81” Remington 700 ADL shoots well with my current load and equipment but I was curious what some of you are using for neck tensions, if you’re using the expander dies and not the expander ball on a normal sizing die, and if so, did you notice a difference once you switched. I’m ready to pull the trigger on getting some sizing dies if it’s working better in most cases.

Thanks!

[Shadow9mm]

Only every used the expander ball. I always figured consistent tension was the goal. Never saw much if any testing on specific amounts of neck tension. Let us know how it goes.

[44 AMP]

I use the expander die for "straight" wall cases. For bottle necked cases, I don't, just use the expander ball on the decapping stem.

[Benchguy]

The YouToubers are all over it. A bunch of the content is a few years old but it’s still mentioned in newer content as well. I’m a little late to the game but my real goal is to see if help my son in stopping the bullet travel he’s seeing in his AR10 gas gun when the bolt cycles.

[Shadow9mm]

Increasing the neck tension could help, having bullets move when chambering is less than ideal.

Personally I just crimp all loads that are intended for a gas gun. I use the lee factory collet crimp, with a light crimp, works well.

johnnies reloading bench did a couple of videos testing the lee factory crimp die. I cant remember the exact results, I need to re-watch, but here they are.

223 https://www.youtube.com/watch?v=wnZWv38cNKw
300blkhttps://www.youtube.com/watch?v=BOBPMSMNOeE

Just the crimp die itself is pretty cheap like $14. https://www.midwayusa.com/product/1016833587?pid=448813

Really curious to see where you search lands you, please keep us updated.

[zeke]

Am confused over whether the neck measurements are inside or outside? It does appear .221 - .218 = .003 .006 may be considered tight

Before getting comp seater dies, used expanding plugs of smaller calibers to just get the case mouth opened up with plugs meant for lead bullets. Increased the neck tension while getting the bullet started straighter. Also eliminated chance of expander ball pulling case neck akilter.

For the cartridges used most, am invested in bushing dies and comp seaters. The necks don't get expanded unless need to use a specific trim operation.

Either way, am using more case neck tension than most would agree with, but you need to be able to seat the bullet concentrically.

[BJung]

I currently use the LEE collet neck sizing die or a FL die with the de-capping pin/ expander ball removed. With the FL die, I follow up using a mandrel. My reason for this is 1: the expander will cause concentricity issues if the hole the de-capping pin is screwed through is not concentric with the die body and case. And 2: the case wall thickness are most likely not concentric. And so, neck tension will vary. Resizing the ID of the neck helps remedy this. I have not decided to neck turn yet because I think the bullet is centered enough to the bore and the rifle has other tolerance variances that make neck turning neglgible. I might add graphite to the inside of the necks.

[Benchguy]

Zeke, the measurements are inside dimensions. Correct me if I’m wrong but at .218 ID, after running through the sizing die with the expander ball, it gives me the .006 as the bullets measure .224. This seems like a lot, but it is shooting great.

Shadow9mm, my son is thinking the crimping die is a good option, but I also think the alignment of expander mandrels is possibly the best option for any possible runout. My personal method can use improvement in consistency. I can’t change what happens inside the die so it seems like the mandrel dies reduces or eliminates what I can’t.

[Shadow9mm]

Originally Posted by Benchguy

Zeke, the measurements are inside dimensions. Correct me if I’m wrong but at .218 ID, after running through the sizing die with the expander ball, it gives me the .006 as the bullets measure .224. This seems like a lot, but it is shooting great.

Shadow9mm, my son is thinking the crimping die is a good option, but I also think the alignment of expander mandrels is possibly the best option for any possible runout. My personal method can use improvement in consistency. I can’t change what happens inside the die so it seems like the mandrel dies reduces or eliminates what I can’t.

Crud, here we go.

Ok so let me ask this, if the round is getting banged around hard enough to unseat the bullet, what effect do you think that's having on the concentricity?

Into the weeds. I would also ask if you have a concentricity gauge? What your current runout is, and what kind of improvement you are hoping to see with a expander die.

I can see advantages to controlling neck tension this way, however 0.006 seems fairly heavy already. My understanding was that 0.002 to 0.003 was fairy common. I don't think going tighter is the answer in this case.

Perhaps a combination of both of your just itching to try expander dies. But I would focus on stopping the bullet movement before worrying about concentricity aa i have found seating depth to play a significant role in accuracy.


Johnnies reloading bench did a cool die test comparing ball expander to expander dies for concentricity, kind of what your looking at minus the neck tension issue. https://youtu.be/zIK5wq5vuSU?si=ZmmelklRpx6oyB1K

[zeke]

No you are right, and appreciate the correction. Some dies have self centering carbide expander balls, and on others have deliberately loosened the locking ring. The only lee dies am familiar with are several pistol dies and they do not allow this.

When sizing now, am using undersize expander balls installed to be able to deprime but not drag on the neck. The only neck expanding is done by the bullet.

[FrankenMauser]

I use expander dies for a select number of (non-handgun) cartridges.
Two of the notable ones are .444 Marlin and .44 Mag.
It just makes bullet seating easier and more concentric, even if using jacketed bullets.

I do, however, now use 'bushing bump neck sizing dies' for a couple cartridges, to get the right neck diameter and bullet tension for a couple cartridges.
I first tried it for 6.5-284 Norma, because my standard FL sizing die was giving too much neck tension. Once the 'bushing bump' die helped there, I bought a couple more for other things.

[tangolima]

How were the IDs measured? With pin gauges? 0.218” for 0.224” bullet is a bit too tight.

I haven't heard of expander die for non-straight wall cartridges. The expander ball may be under sized. I expect diameter of 0.222”, measured with micrometer, to give brass neck ID of 0.221”.

With tight bullet hold of 0.006” you still have bullet set back after chambering? I'm afraid nothing else can be done to help. You may have coal too long that bullet hits the riflings.

-TL

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[jetinteriorguy]

I’m a big fan of full length body sizing with a Redding body only die followed by the Lee collet neck sizing die. It keeps runout under .001” so consistently I stopped even checking anymore. I’ve probably checked well over a thousand rounds in all the calibers I load with this method to have this much faith in this system.

[Benchguy]

So I have to apologize for adding two different things to the original post. For the measurements I have given, that is for my 22-250 and measured with my micrometer. I don’t have a runout, concentricity gauge. I did turn the case as I measured it I know this is a poor man’s way and not a good way to measure.

My son’s case mouths haven’t been measured by myself so I’m not sure what those numbers look like. It is the 6.5 Creedmore. I’ll get those measurements and add my findings.

This forum is so helpful! Always a pleasure to ask and get everyone’s input and feedback!

Thank you!
James

[tangolima]

Measuring ID is tricky even with micrometer. Pin gauges results are better. Indirect measurement based on OD is even better.

Measure neck OD before seating bullet. Measure again after. The difference is the bullet hold. I look for 0.002” to 0.003” for auto loader. For bolt gun I can go slightly less.

For precision ammo, especially calibers with hard-to-find or expensive brass, I use bushing die with no expander ball. The neck is turned to have uniform thickness. Bushing diameter controls bullet hold.

-TL

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[Benchguy]

Tangolima, that method of measurement gives .002-.003, like you mentioned, on both cartridges. Seems taking the ID is misleading.?

The bushing dies are for resizing necks only, or shoulder bump too? I’m just learning past the OG style sizing dies.

TY!

[Shadow9mm]

Originally Posted by Benchguy

Tangolima, that method of measurement gives .002-.003, like you mentioned, on both cartridges. Seems taking the ID is misleading.?

The bushing dies are for resizing necks only, or shoulder bump too? I’m just learning past the OG style sizing dies.

TY!

bushing dies are generally a full length sizing die, however instead of using an expander ball to set the neck tension, they use a bushing on the outside to control the outside neck diameter. The idea is rather than squeezing the neck down below dimension and then using the expander ball to open it back up, you can simply compress the neck to the exact right size from the outside. This works the brass less when sizing although I have not been able to find much info on how much it extends brass life.

This can create a problem however if the thickness of the brass in the neck is not consistent, causing variances in id diameter and or offsetting the bullet if the brass is thicker on one side of the neck than the other. The most common remedy for that issue is neck turning to create a consistent neck wall thickness. For me it causes more problems that it solves, some people swear by it, YMMV.

[tangolima]

Anvil placement creates uncertainty in ID measurement. You may be measuring the length of a chord, instead of the diameter (the longest chord). That's reason for pin gauge and air gauge.

The 0.002” to 0.003” bullet hold is traditional figure for .30 cal. It corresponds to 0.5% to 1% stretch of the circumference. Apparently the same number applied to smaller calibers may not be appropriate. For .22 cal, I would adjust to under 0.002".

I turn neck for better consistency on regular basis, even when using regular FL sizer. Bushing die just make it better. Uneven neck thickness is no good for business, is it?

-TL

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[Unclenick]

Benchguy,

I am going to guess you are using a caliper rather than a micrometer, though the terms have a history of conflation. In current common use, the former has measuring jaws that slide open and closed, while the latter is opened and closed by screwing its measuring surfaces in and out by rotating a thimble with measuring graduations on it. The problem with measuring IDs with the inside jaws of a caliper is that the jaws have a small flat ground onto them, and while the distance measured is between the inside edges of those small flats, it is the outside edges that make primary contact with the sides of a hole. So, it is not uncommon for them to report a thousandth or two smaller values than the actual diameter of the hole being measured. The smaller the hole, the bigger the error.



A second point to make is that brass has some elasticity, so it is pretty common, after running an expander through a neck, to have the ID spring back about 0.001" smaller than the expander is.

The main problem with the standard pull-through expanders is they can pull the neck of a case off-axis with the rest of the case body. When this happens, the neck and the seated bullet can be slightly angled to the side of the case body axis. That opens groups up because the bullet starts into the bore misaligned with it, and misaligned bullets seldom straighten up completely. They go down the bore with their center of gravity orbiting the bore axis rather than spinning on the bore axis, and when they exit the muzzle, this causes it to drift away from the bore line laterally.

A cartridge that has its case body, neck, and bullet aligned on the same axis is perfectly concentric (circular cross-sections taken anywhere along its length share the same centerline). This provides optimal alignment of the bullet with the bore in the chamber and, with some bullet designs, can cut over an MOA from their dispersion on the target. Making a concentric cartridge takes some extra doing. Jetinteriorguy used the Redding Body Die, which sizes the case body and shoulder but leaves the neck alone, followed by a Lee Collet Die, which sizes the neck around a mandrel to control its inside diameter. This is superior to achieving the final neck ID with a pull-through expander, which is on most sizing dies, as illustrated in this old video. The video doesn't use the body die, but rather just shows the difference in neck concentricity and handling.

Once your case has a straight neck, you want to seat your bullets in a fashion that keeps them lined up straight. I usually use the Redding Competition Seating Die for this, but the Forster Bench Rest seating die is almost the same. The latter lacks a floating seating stem, but it can handle compressing loads, which the Redding cannot do without wearing part of it. So, your die choice depends on your powder charge choice.

Another method of doing this is to use a separate Lyman M-die for your chambering. These are expander dies and are made for bottleneck and straight wall cases. Unlike the Lee Universal Expander Die, which simply funnels a case mouth to accommodate a bullet without scraping its sides, the Lyman dies expand a few thousandths for a short cylindrical length before the case mouth meets its flaring surface. That puts a little short step in the case that allows you to set a bullet into its mouth, sitting straight up and down. It stays that way when you start the cartridge into the seating die. Having the bullet concentric with the case as seating starts tends to keep it that way. I have been able to seat bullets with a standard RCBS seating die that stay within 0.001" runout (a good number) just by starting with the Lyman M-die and getting the bullets to go in straight. For jacketed bullets, I form only the step and no flare, as they don't need it. The seating die can then be set so its crimp shoulder flattens the flare out. But loading for rifles that have a wide enough neck portion of their chambers, you can leave it unstraightened to help center the bullet with the bore.

[Shadow9mm]

Originally Posted by tangolima

Anvil placement creates uncertainty in ID measurement. You may be measuring the length of a chord, instead of the diameter (the longest chord). That's reason for pin gauge and air gauge.

The 0.002” to 0.003” bullet hold is traditional figure for .30 cal. It corresponds to 0.5% to 1% stretch of the circumference. Apparently the same number applied to smaller calibers may not be appropriate. For .22 cal, I would adjust to under 0.002".

I turn neck for better consistency on regular basis, even when using regular FL sizer. Bushing die just make it better. Uneven neck thickness is no good for business, is it?

-TL

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What do you use to turn necks? How much of a difference do you feel lit makes?

[Unclenick]

One of the authors in the 1995 Precision Shooting Reloading Guide had a 300 WM that shot 2 moa no matter what load adjustments he made. Then one day he tried neck turning and it dropped to 1 moa. No doubt, this is about the particular gun and chamber, mainly, but in some combinations, it can matter. I had something similar happen with flash hole deburring, but only for one particular powder and no others in the same gun.

The way to see if it will help is to buy some premium cases like Lapua that are already very uniform at the neck. If they shoot no better than what you have been using, neck conectricity and flash hol deburring are not among your problems.

[tangolima]

I have a cheap rcbs turner with a bunch of pilots.

I don't have a number to show improvement in groups fired. I do measure neck thickness variation at different points around the brass mouth. Before turning, variation of 0.0015" is common. After turning it will be close to zero.

Occasionally I need to load with bullet so over sized that it won't chamber unless I thin out the neck to make room. The turner is handy for such off-brand use.

-TL

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[Benchguy]

You are correct, unclenick, I misspoke. I used a caliper to measure the neck ID. I ordered a pair of depriming and decapping dies, so I just need to figure out what direction to go with the other dies to complete the setup. We have a custom rifle being built right now and it will be a good idea to be ready for reloading for it. It’s chambered in 6ARC. I am just starting to gather knowledge on how to bring out the best in it. These conversations are great for me. Thank you!

How many presses are on your bench? Thinking about adding another one. We have an old Pacific and an RCBS Turret Press.

[tangolima]

Calipers eh? Beware of its uncertainty. In untrained hands it can easily be +/-0.001" if not more. Micrometer with thimble can go down to +/-0.0001". I use the latter when dealing with critical measurements.

-TL

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[GeauxTide]

In over 50 years of loading, I've always used the expander that comes with the dies. 38, 357, 41mag, 44spl, 44mag, 45acp, 45Colt.