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Expander for neck tension

RTTY

Private
Minuteman
Sep 5, 2023
51
7
Italy
Hello!
I'm looking for an expander die and mandrells kit for my 6,5mm cartdridge.
I'm a bit undecided about the brand for my purchase.
My reference brands are:
ARC
21st century
PMA
K&M Powerstroke

Can advice me for select the best kit?

Thanks
 
Hello, thanks for the reply, fon now I don't wanto to turning the neck, maybe I make a wrong thing, but for now only neck tensione.
 
Hello, thanks for the reply, fon now I don't wanto to turning the neck, maybe I make a wrong thing, but for now only neck tensione.

Just a heads up, as it'll get confusing if you're not aware. When people say "turning" and "expander"......historically, mandrels were almost solely used to expand a case before neck turning, and then as a pilot for neck turning.

Expander mandrels are .001 under bullet diameter and Turning mandrels are .002 under bullet diameter. So that's what people mean when they use the term expander or turning mandrel. Once shooters started using these two types of mandrels to set their final interference fit and not just for turning, companies started making mandrels in sizes other than .001 and .002 under. These other sizes are just referred to as mandrels and their size given.

But, you will still see retailers selling expander and turning mandrels as well as reloaders referencing them as such when talking about .001 and .002 under.
 
I have had good luck in 6.5CM with a 21st Century black nitride turning arbor. It's 0.002" under bullet diameter. For some reason the 22-cal turning arbor (0.222" diameter) didn't work the same, so I went down to 0.221" in stainless. I will likely have a custom carbide mandrel ground in 0.221" at some point, the stainless galls up and I have to clean it off every 50-100 cases.
 
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This is awesome if it’ll work, I could find carbide pin gauges far easier than mandrels

If you end up with something like a Porter or other collet die and want to get your own pins, keep in mind you'll probably need to either angle or round off the end going into the case mouth. Just using flat end gauge pins, you'll have to go slow or physically line up the case with your hand, otherwise the pin will hit/damage the face of the case mouth.
 
Hello!
Porter is not essy to find on EU, 21st is a bit easy.
ARC, PMA, k&m, Wilson are more easy to buy..
So I would to choice from this brands.
 
If you end up with something like a Porter or other collet die and want to get your own pins, keep in mind you'll probably need to either angle or round off the end going into the case mouth. Just using flat end gauge pins, you'll have to go slow or physically line up the case with your hand, otherwise the pin will hit/damage the face of the case mouth.
How would the OP do that ? Just in case he does not know, an easy explanation would help.
 
I have PMA and 21st century. Some are stainless and some are the black nitride. The black nitride is the way to go, or carbide. The stainless is just not as smooth and slick as the black nitride and If I don’t do a good job lubing the necks I can feel it.

I also use the turning mandrels (.002 under bullet diameter).
 
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It's assumed that men have basic mechanical skills.

I wish I was one , instead I wear pink shorts and strut my fat ass trying to pick up boys ..

Huh ?
 
How would the OP do that ? Just in case he does not know, an easy explanation would help.
I use a small belt sander and a cordless drill. Put the gage pin in the cordless drill, spin it in the opposite direction of the belt sander and sand/grind the end of the pin to a gradual taper about 1/" long. The using a polishing wheel on a bench grinder I polish the gage pin to a fine finish. If you don't have the needed equipment to do this then buying the tapered pin gages from PPP ($10.00 ea.) is the way to go.
A lathe is another option.
 
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I use a small belt sander and a cordless drill. Put the gage pin in the cordless drill, spin it in the opposite direction of the belt sander and sand/grind the end of the pin to a gradual taper about 1/" long. The using a polishing wheel on a bench grinder I polish the gage pin to a fine finish. If you don't have the needed equipment to do this then buying the tapered pin gages from PPP ($10.00 ea.) is the way to go.
A lathe is another option.

Don't mind him. He's not actually asking a question. Just being an asshole.
 
Hello!
Porter is not essy to find on EU, 21st is a bit easy.
ARC, PMA, k&m, Wilson are more easy to buy..
So I would to choice from this brands.

I was interested in the Porter but had the same availability concerns. I grabbed the Forster universal bullet puller with a caliber specific collet and bot a series of pin gauges. the pin fit and i am using it to test different pin sizes
Bullet-Pullers.jpg
 
I was interested in the Porter but had the same availability concerns. I grabbed the Forster universal bullet puller with a caliber specific collet and bot a series of pin gauges. the pin fit and i am using it to test different pin sizes
Bullet-Pullers.jpg

Hello Trevor, you can use this stuff like an expander die?
What type of pins you use for expander mandrells?

Please can you explain with more detail?
 
Hello Trevor, you can use this stuff like an expander die?
What type of pins you use for expander mandrells?

Please can you explain with more detail?
He uses the bullet puller die to hold a gauge pin and uses that as the expander.
Just buy the 21st Century set up and be done
 
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Taylorbok has it right.
The difference cost and availability for competitors outside the USA... the Forster and gauge pin might be more available
Here is a example of a collet held pin... F class john is using a Hornady bullet puller I tried one but occasionally the pin would slide the solution was the Forster i could lock the pin down.
I was able to get the gauges pins at a local machine shop. you can also source carbide pin gauges once you narrow down your choice or if like me turn necks i have carbide mandrels for the process
 
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Ok Trevor I understood.
What pins diameter I can select for my 6,5mm bullets?
.263 , .2625 , .262 are right or I can add .2615 and .261?
I use only Lapua brass for my 6,5x47 Lapua; mostly fired even more than 10 times...
But annealled every time.
 
Before buying anything I would think about what you want to do. While their shit is incredibly overpriced , the SAC sizing die with integrated mandrel will save you a ton of time and lever pulls, unless you plan to automate your reloading.

It costs more up front but could save you alot of time down the road. A decent mandrel die and mandrel is gona run you $100 at least anyway, so the cost difference starts to narrow.
 
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Before buying anything I would think about what you want to do. While their shit is incredibly overpriced , the SAC sizing die with integrated mandrel will save you a ton of time and lever pulls, unless you plan to automate your reloading.

It costs more up front but could save you alot of time down the road. A decent mandrel die and mandrel is gona run you $100 at least anyway, so the cost difference starts to narrow.
You do have a point for sure that it will save time. The SAC operates basically the same as an expander ball but being long may have a better chance at keeping the neck straight 🤷‍♂️. Anyway several years ago when I started decapping and expanding in several steps went to a progressive for brass prep and never looked back. I seat bullets on a separate single stage
 
IMO, get the 21st Century KIT. I’m quite happy with mine.

Even with annealing, you are going to run a mandrel into the neck and get some degree of spring back which will likely vary over the number of subsequent firings. So, WTF interference fit is a .002 under bullet diameter going to provide. Yep, WTF knows.

And, bullets vary a small bit by brand and lot, right?

I say this with the assumption that the OP is looking to do what I am….that is, get a very specific degree of interference fit of the neck/bulket without regard for for exactly what size mandrel will provide this.

The kit provides a set of mandrels varying a bit in diameter between them for the caliber of the set.

I’m not sure really how much benefit I reap from this but I’m retired and do try to entertain myself with stuff! lol
 
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Before buying anything I would think about what you want to do. While their shit is incredibly overpriced , the SAC sizing die with integrated mandrel will save you a ton of time and lever pulls, unless you plan to automate your reloading.

It costs more up front but could save you alot of time down the road. A decent mandrel die and mandrel is gona run you $100 at least anyway, so the cost difference starts to narrow.

Hello,
SAC is a great piece of stuff but I reload so little ammunition per year that the time is not a problem for me.
 
You do have a point for sure that it will save time. The SAC operates basically the same as an expander ball but being long may have a better chance at keeping the neck straight 🤷‍♂️. Anyway several years ago when I started decapping and expanding in several steps went to a progressive for brass prep and never looked back. I seat bullets on a separate single stage

Hello, you use a progressive press with decapping die, full die without expander ball, and expander mandrell?

Wich brand of progressive you use for this?
 
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IMO, get the 21st Century KIT. I’m quite happy with mine.

Even with annealing, you are going to run a mandrel into the neck and get some degree of spring back which will likely vary over the number of subsequent firings. So, WTF interference fit is a .002 under bullet diameter going to provide. Yep, WTF knows.

And, bullets vary a small bit by brand and lot, right?

I say this with the assumption that the OP is looking to do what I am….that is, get a very specific degree of interference fit of the neck/bulket without regard for for exactly what size mandrel will provide this.

The kit provides a set of mandrels varying a bit in diameter between them for the caliber of the set.

I’m not sure really how much benefit I reap from this but I’m retired and do try to entertain myself with stuff! lol

21st Century is a most complete kit, but for non competitive user likes me that use only one brand of brass and only one brand and type of bullets the numbers of dimension of mandrells are 2 or 3 less (.263 , .2625 , .262) than the bullet diameter...
What do you think ?
 
I use a small belt sander and a cordless drill. Put the gage pin in the cordless drill, spin it in the opposite direction of the belt sander and sand/grind the end of the pin to a gradual taper about 1/" long. The using a polishing wheel on a bench grinder I polish the gage pin to a fine finish. If you don't have the needed equipment to do this then buying the tapered pin gages from PPP ($10.00 ea.) is the way to go.
A lathe is another option.
Thanks, easy enough that anyone can do that . I like the idea of finishing with a buffing wheel .
 
You do have a point for sure that it will save time. The SAC operates basically the same as an expander ball but being long may have a better chance at keeping the neck straight 🤷‍♂️. Anyway several years ago when I started decapping and expanding in several steps went to a progressive for brass prep and never looked back. I seat bullets on a separate single stage
Its nothing like an expander ball. Its an integrated Mandrel. No different than a separate sizing and mandrel die.
 
21st Century is a most complete kit, but for non competitive user likes me that use only one brand of brass and only one brand and type of bullets the numbers of dimension of mandrells are 2 or 3 less (.263 , .2625 , .262) than the bullet diameter...
What do you think ?
You need to make that decision. Its based on the type of brass, are you annealing, how much neck tension you want, and honestly trial and error. I use .2410 for 6mm and .2630 for 6.5mm after trying a bunch and getting the most consistent results. On paper it looks like there is more neck tension with the 6mm but it could just be springback/different brands of brass behaving different. You really wont know until you load up and see the results.
 
for non competitive user likes me that use only one brand of brass and only one brand and type of bullets the numbers of dimension of mandrells are 2 or 3 less (.263 , .2625 , .262) than the bullet diameter...
What do you think ?
You need to make that decision.
What he said....yeah, the kit is a good bit of change and I probably won't ever use all of the mandrels in it, but I'm lazy and I hate waiting on stuff to be delivered if I find I need something so...I got the kit.

Yeah, you could def order only a handful of them around your bullet diameter and if you find you need one you don't have, you can always just order that one singly also
 
Best bet is to find someone using the same brass as you plan to, and see what they use for a given application. That's what I did to save to expense of buying a bunch of them. Let someone else do the hard work.
 
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Its nothing like an expander ball. Its an integrated Mandrel. No different than a separate sizing and mandrel die.
It's literally a long expander button that is drawn through the neck. I don't see it causing any problems. IMO the only advantage to an expander mandrel over a ball is the ability to change the case ID based on the mandrel size. Some say it helps with concentricity but I just can't imagine how it would make a difference.
EXPANDER-MANDRELS.png

Marketing%2C+2021+Master+AssemblyV1.jpg
 
Hello, you use a progressive press with decapping die, full die without expander ball, and expander mandrell?

Wich brand of progressive you use for this?
Yes. I use a Dillon 750. I actually prime on it also, it's given me great results
 
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You need to make that decision. Its based on the type of brass, are you annealing, how much neck tension you want, and honestly trial and error. I use .2410 for 6mm and .2630 for 6.5mm after trying a bunch and getting the most consistent results. On paper it looks like there is more neck tension with the 6mm but it could just be springback/different brands of brass behaving different. You really wont know until you load up and see the results.
Sorry for delay @DeathBeforeDismount ,
reading your word I understand that are plenty of sapience, I try with .263"...
But how I can say if the .263" are the right mandrell or no?

Thanks!
 
What he said....yeah, the kit is a good bit of change and I probably won't ever use all of the mandrels in it, but I'm lazy and I hate waiting on stuff to be delivered if I find I need something so...I got the kit.

Yeah, you could def order only a handful of them around your bullet diameter and if you find you need one you don't have, you can always just order that one singly also
Sorry for delay @Baron23 ,
the .263" are for my reload tests
 
For all:
I read your comment about 21st Century, these are a great choice for expander and mandrells, but I look for these other brands becouse 21st are hard to find on Italy:
K&N
ARC Ballistics

Wath are your opinion about this two brands/products?

Thanks
 
I have the K&M V2 both two row and three row. The mandrel holder/vertical fine adjuster works for both. The hash marks/indicators on the mandrel holder is a nice detail, but it is kind of a gimmick. The straight portion of the mandrel itself is long enough that you really don't need hash marks on the fine vertical adjuster to dial in the specific vertical height of the mandrel. The mandrel die body itself has holes so you can visually set the vertical height of the mandrel so that the case mouth doesn't contact the top of the mandrel, rendering the harsh marks pointless (my opinion).

There's a groove right before the top of the mandrel that collects debris (whether it's left over carbon or brass flakes) which is nice but the area that transitions from the tapered lead in to the straight portion of the mandrel can also collect a tiny bit of debris and brass particles. Doesn't affect anything as far as I can tell.

Not really much else to say about it other than it works, diameter of mandrels are as advertised (for the ones I purchased; measured with vernier micrometer) and order a set of mandrels so you can account for brass spring back.

Pic below of a K&M 30 cal .0025 mandrel at 10x magnification, you can see the brass particle collecting at the transition area.
1710871316918.png
 
But how I can say if the .263" are the right mandrell or no?
You can't...that's why they sell kits and that's why if you want to buy individual mandrels my suggestion is to buy a few.

Its like this...you run a mandrel into the neck of the case and pull it out.

What's the inside diameter after doing this? Due to spring back (which can vary from case brand to brand and over the lift of reloading a particular case), WTF knows.

Say you want .002 interference fit between the neck and the bullet (most often referred to as neck tension). You Berger 140 HT .264 bullets measure .2635 on the bearing surface using your very good calipers or a micrometer. So, you want the resultant inside diameter to be .2615 (.002 under bullet diameter). There is going to be (or likely to be) spring back to some degree , so you you want a mandrel some bit larger than than .2615....but how much? Well, beats the fuck out of me.

This is why I have a set of mandrels .0005 apart and pin gauges the same. If I select a mandrel, run it, and then with pin gauges I determine that I don't have the .002 interference fit I want, I try a different size mandrel and then measure and do this iteratively until I get the I.D. I want for that batch of brass. Then just run 'em.

This is why I have never understood the value of companies offering carbide mandrel (for example) in one size only (.002 under bullet diameter).

There are sure to be many who say I don't need to do this...just run a mandrel that's .002 under bullet bearing surface measurement but this is my approach. Understand, I don't reload hundreds of rounds during the week for a competition that weekend and I'm retired with time on my hands. My reloading process is just one that interests me and trying to produce the most consistent ammo I can is its own reward to me.

Cheers
 
You can't...that's why they sell kits and that's why if you want to buy individual mandrels my suggestion is to buy a few.

Its like this...you run a mandrel into the neck of the case and pull it out.

What's the inside diameter after doing this? Due to spring back (which can vary from case brand to brand and over the lift of reloading a particular case), WTF knows.

Say you want .002 interference fit between the neck and the bullet (most often referred to as neck tension). You Berger 140 HT .264 bullets measure .2635 on the bearing surface using your very good calipers or a micrometer. So, you want the resultant inside diameter to be .2615 (.002 under bullet diameter). There is going to be (or likely to be) spring back to some degree , so you you want a mandrel some bit larger than than .2615....but how much? Well, beats the fuck out of me.

This is why I have a set of mandrels .0005 apart and pin gauges the same. If I select a mandrel, run it, and then with pin gauges I determine that I don't have the .002 interference fit I want, I try a different size mandrel and then measure and do this iteratively until I get the I.D. I want for that batch of brass. Then just run 'em.

This is why I have never understood the value of companies offering carbide mandrel (for example) in one size only (.002 under bullet diameter).

There are sure to be many who say I don't need to do this...just run a mandrel that's .002 under bullet bearing surface measurement but this is my approach. Understand, I don't reload hundreds of rounds during the week for a competition that weekend and I'm retired with time on my hands. My reloading process is just one that interests me and trying to produce the most consistent ammo I can is its own reward to me.

Cheers
The search for a range of carbide mandrels is something that stymied me too, which is why I'm intrigued by the collet option. Heck, even electrical tape could make a carbide pin gauge work in the 21st Century die body, the hardest part is getting a reasonable taper ground on the gauge.
 
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I have the K&M V2 both two row and three row. The mandrel holder/vertical fine adjuster works for both. The hash marks/indicators on the mandrel holder is a nice detail, but it is kind of a gimmick. The straight portion of the mandrel itself is long enough that you really don't need hash marks on the fine vertical adjuster to dial in the specific vertical height of the mandrel. The mandrel die body itself has holes so you can visually set the vertical height of the mandrel so that the case mouth doesn't contact the top of the mandrel, rendering the harsh marks pointless (my opinion).

There's a groove right before the top of the mandrel that collects debris (whether it's left over carbon or brass flakes) which is nice but the area that transitions from the tapered lead in to the straight portion of the mandrel can also collect a tiny bit of debris and brass particles. Doesn't affect anything as far as I can tell.

Not really much else to say about it other than it works, diameter of mandrels are as advertised (for the ones I purchased; measured with vernier micrometer) and order a set of mandrels so you can account for brass spring back.

Pic below of a K&M 30 cal .0025 mandrel at 10x magnification, you can see the brass particle collecting at the transition area.
View attachment 8376569

Thanks for the report!
 
You can't...that's why they sell kits and that's why if you want to buy individual mandrels my suggestion is to buy a few.

Its like this...you run a mandrel into the neck of the case and pull it out.

What's the inside diameter after doing this? Due to spring back (which can vary from case brand to brand and over the lift of reloading a particular case), WTF knows.

Say you want .002 interference fit between the neck and the bullet (most often referred to as neck tension). You Berger 140 HT .264 bullets measure .2635 on the bearing surface using your very good calipers or a micrometer. So, you want the resultant inside diameter to be .2615 (.002 under bullet diameter). There is going to be (or likely to be) spring back to some degree , so you you want a mandrel some bit larger than than .2615....but how much? Well, beats the fuck out of me.

This is why I have a set of mandrels .0005 apart and pin gauges the same. If I select a mandrel, run it, and then with pin gauges I determine that I don't have the .002 interference fit I want, I try a different size mandrel and then measure and do this iteratively until I get the I.D. I want for that batch of brass. Then just run 'em.

This is why I have never understood the value of companies offering carbide mandrel (for example) in one size only (.002 under bullet diameter).

There are sure to be many who say I don't need to do this...just run a mandrel that's .002 under bullet bearing surface measurement but this is my approach. Understand, I don't reload hundreds of rounds during the week for a competition that weekend and I'm retired with time on my hands. My reloading process is just one that interests me and trying to produce the most consistent ammo I can is its own reward to me.

Cheers
My RCBS Full Length die size the neck with an internal diameter of .262", I think that like your suggestion the .263" and .262"mandrells are the good job!
 
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