Sizing die with Mandrel vs Separate Mandrel Die

[George of Lydda]

I am just getting in to reloading so I apologize if this is a dumb question.

I am looking for dies for my first reloading press (419 Zero). I like what I see with the SAC sizing dies with the expander mandrels as I have a universal decapping die.

My question is, is there a downside to having the mandrel in the sizing die compared to having a separate expander mandrel die? I am hoping to maximize the cartridges I can reload on each zero tool head. I haven't seen anyone discuss this and maybe that's because I am missing something with my non-existent experience on the subject.

 

[NiteQwill]

Time. If you do separately, you increase prep time.

Many of us run the SAC and Area419 dies with mandrel. They work very well.

Size/decapper/mandrel = more time doing other stuff.

 

[George of Lydda]

Okay that's what I was thinking, I'd like to save time but not at the expense of measurable precision.

 

[NiteQwill]

Okay that's what I was thinking, I'd like to save time but not at the expense of measurable precision.

The SAC dies are top-tier, gucci dies... you're not losing any precision with it.

 

[OREGUN]

I SAC die with mandrel…so one stroke of the press does decapping, sizing, and mandrelling. Results are good and time is saved. I never understood the point of dedicated decaping and now I hate it when I have to rerun brass over a mandrel (Odd ball caliber for which I don’t have the fancy die). ETA: no change in precision when I switch from a two die process to the SAC die.

 

[George of Lydda]

Awesome. Really appreciate the responses.

 

[simonp]

Guess I’m an odd man out, I use a universal decapper because I run brass through that first then clean it then I run it through a sizing for then mandrel.

 

[NiteQwill]

Guess I’m an odd man out, I use a universal decapper because I run brass through that first then clean it then I run it through a sizing for then mandrel.

I think that's fine. I do have a FW Arms decapper that is awesome. But you really don't gain anything by doing it beforehand. Just a time issue.

 

[Haney]

Guess I’m an odd man out, I use a universal decapper because I run brass through that first then clean it then I run it through a sizing for then mandrel.

Plenty of folks do it like you do . Keeps the dirt out of the good dies .

 

[OREGUN]

Guess I’m an odd man out, I use a universal decapper because I run brass through that first then clean it then I run it through a sizing for then mandrel.

Lots of folks do it that way. Totally a preference thing. I go for fewer touches over spotless primer pockets. So, tumble, anneal, size-decap-mandrel is the basics for me.

 

[Dil pickle]

I love my SAC dies. Patiently waiting for them to release the long action stuff. I have micron and Redding dies that I use for the LA stuff and then run them through a mandrel after.

 

[BuildingConceptsllc]

Guess I’m an odd man out, I use a universal decapper because I run brass through that first then clean it then I run it through a sizing for then mandrel.

Yup, that's what I do too. I don't even use a mandrel unless there's a reason to on fired brass. I just use my bushing die and that's it. With a correct bushing, a mandrel gave me zero benefit. I tested it with 50 rounds of bushing die and 50 rounds of bushing die + mandrel and the there was no difference at all in accuracy or SD, so I stopped using a mandrel unless I had a dented neck or something.

 

[BuildingConceptsllc]

Plenty of folks do it like you do . Keeps the dirt out of the good dies .

This is why I do it that way.

 

[Baron23]

Lots of folks do it that way. Totally a preference thing. I go for fewer touches over spotless primer pockets. So, tumble, anneal, size-decap-mandrel is the basics for me.

Please, can you explain how the mandrel part of the SAC due works to decap and mandrel. I’ve looked at the drawings on their site and I see bushings, a big decapping pin held in the collet, and I see what looks like a mandrel in another pic but I don’t see how all of that works to decap, size, and mandrel in a single stroke.

I’m probably badly misunderstanding this. Can you explain? Or am I being a total idiot?

 

[NiteQwill]

Please, can you explain how the mandrel part of the SAC due works to decap and mandrel. I’ve looked at the drawings on their site and I see bushings, a big decapping pin held in the collet, and I see what looks like a mandrel in another pic but I don’t see how all of that works to decap, size, and mandrel in a single stroke.

I’m probably badly misunderstanding this. Can you explain? Or am I being a total idiot?

The SAC works by decapping, then placing the neck into the bushing, followed by a mandrel on the upstroke. The difference between a expander ball and the mandrel in the SAC is the geometry (think: longer).

 

[CK1.0]

I FL size and decap at the same time (no expander ball) and then run the cases under a mandrel die in a second step.

The thing behind doing it this way is that the mandrel is allowed to push any imperfections in the necks to the outside... so the inside is as close to perfect as can be for when it's time to seat bullets.

I don't mind doing the mandrel as an extra step as it goes by quickly and is probably the easiest part of my process (TiNi mandrel, no lube needed).

Plus, I do it after I've already tumbled off the lube from sizing... so it adds an extra layer of QC to remove/fix any dents in the necks and/or case mouths that I may have picked up while tumbling post-sizing (this happens much more than many might think, many of the sized cases don’t come out of the tumbler the same way they went in fresh out of the FL die, the mandrel is like the "undo button" and makes them right again if any got out of whack).

I've seen an improvement both in SD/ES numbers and what I get downrange doing it this way.

 

[Baron23]

The SAC works by decapping, then placing the neck into the bushing, followed by a mandrel on the upstroke. The difference between a expander ball and the mandrel in the SAC is the geometry (think: longer).

So, decapping pin screws into the mandrel and mandrel opens the neck (after bushing) on the upstroke like an expander ball?

I look at these pics from SAC's site and I still don't understand where the mandrel is or how this die decapps and mandrels on one stroke. I must be more dumb that usual today! haha

While this is the pic that they show of their mandrel for this die:

 

[CK1.0]

SAC calls it a “mandrel” but in reality it’s really just an improved expander-ball design, Mighty Armory does the same kind of thing with their dies…

Theoretically a FL die can’t really size and mandrel at the same time without the brass getting stuck, so they have to leave a few thou of play between the engagement of the walls of the die body and the engagement of the “mandrel” against the brass.

 

[OREGUN]

Those are diagrams of the modular sizing die. Imagine if the caliber specific decapping pin in your diagram had a section that was ground to a specific diameter, like a mandrel, in the middle of it.

 

[OREGUN]

SAC calls it a “mandrel” but in reality it’s really just an improved expander-ball design, Mighty Armory does the same kind of thing with their dies…

Theoretically a FL die can’t really size and mandrel at the same time without the brass getting stuck, so they have to leave a few thou of play between the engagement of the walls of the die body and the engagement of the “mandrel” against the brass.

That doesn’t make any sense. It doesn’t have to be any play or any thousands left anywhere. You just have to pull the brass down out of the neck bushing before you start running it over the mandrel.

 

[CK1.0]

That doesn’t make any sense. It doesn’t have to be any play or any thousands left anywhere. You just have to pull the brass down out of the neck bushing before you start running it over the mandrel.

Well, then the SAC die works exactly the same as an expander-ball, first the die body squashes the neck down before it’s then expanded as the “mandrel” is pulled through, pulling up on the shoulder on its way out (which is one of the things using a traditional mandrel avoids).

 

[Hawk in WY]

I use a mandrel as a separate step because I was finding pulling the sizing button (and maybe a mandrel) up to expand the neck was causing an inconsistent shoulder bump. Not sure why, but I'm guessing the shoulder is more able to resist pressure against downward force than upward.

 

[alamo5000]

A little bit of a different perspective on this than has already been expressed. In my personal experience it all depends on the die you are using. At present I decap, tumble, anneal, resize, then expand using a mandrel. The last two steps are pretty much just one extra pull as I use a turret press. If I had a progressive of some sort it wouldn't even add any steps.

I am now almost all the way over to using Mighty Armory dies precisely because I really like their expander design. What a separate mandrel does do is allow for adjustability in neck tension. This is important in load development for sure, and maybe even as your brass gets fired a few times (supposedly, in theory).

Another reason I do it like I do it is because of the dreaded stuck case. It doesn't happen all the time, but when it does it sucks. If you don't have an expander in your die you can just knock the case right out and carry on. I have to admit that I have destroyed a few expanders over time in various die types. For me using a separate mandrel allows for adjustment if needed (or experimentation), as well as being a precaution type of thing against stuck cases.

As for actual shooting, once you get a good load where everything is where it's supposed to be, with a good quality die, there will be little difference to 99% of shooters between separating the two processes or just using the expander during resizing (generally speaking).

 

[KnowNothing256]

SAC calls it a “mandrel” but in reality it’s really just an improved expander-ball design, Mighty Armory does the same kind of thing with their dies…

Theoretically a FL die can’t really size and mandrel at the same time without the brass getting stuck, so they have to leave a few thou of play between the engagement of the walls of the die body and the engagement of the “mandrel” against the brass.

That doesn’t make any sense. It doesn’t have to be any play or any thousands left anywhere. You just have to pull the brass down out of the neck bushing before you start running it over the mandrel.

There might be a disconnect here, this actually made sense to me. The "same time" statement I think refers to literal simultaneous action of the sizing down (from the die body/bushing) and the expanding (from the mandrel). You actually can do this, the Lee Collet Die does it, but to @CK1.0's point, the two surfaces can't be sliding up/down on the case neck at the same time (which the Collet Die avoids). If you did that, you'd have to have perfectly consistent neck wall thickness, and the die would have to be set up to match; this is because when both the outside and inside sizing operations are touching brass at the same time, you're sandwiching the neck brass between the two surfaces. Hence the comment about needing several thou clearance.

Basically, I agree 100% with all of the bolded statements above; I think y'all are both thinking about the internals of the die correctly. The SAC is certainly a premium product, but I do somewhat resent them calling it a mandrel to try to avoid the negative connotations of an expander ball, despite using an essentially identical operation.

 

[Baron23]

Those are diagrams of the modular sizing die. Imagine if the caliber specific decapping pin in your diagram had a section that was ground to a specific diameter, like a mandrel, in the middle of it.

Ok, found this pic of mandrel/decapping die combo...and I'm still not sure if I understand. It appears that on the down stroke, it decaps and the bushing compresses neck diameter when the pin/mandrel has the narrow section in the neck (section in the green rectangle)....then on the upstroke, it pulls the mandrel section (red rectangle) through the neck thus opening it back up to the desired I.D.

So, how is this really other than an expander ball with an extended parallel section?

And I note, these decapping pin/mandrel are for the most part out of stock and only come in a couple of diameters per cartridge family?? E.g. image below.

As said, I'm no expert at reloading but I favored having a set of mandrels so I can fine tune my neck I.D. based on exactly how much spring back I'm getting on particular brass. So, I have a 21st Century mandrel die and mandrel kit (see below) and do this as a separate step. Probably overkill (well, def overkill) and I will prob not use the majority of these mandrels....but wow, I'm def set if I need them! hahaha

Mandrel Kit

I think I understand the SAC die...vaguely (haha)...now.

Thanks for your patience in trying to explain to me.

Cheers

 

[6.5SH]

Unlike an expander ball the entire length of the neck will be on their mandrel style expander at the same time. So I still think it's fair to call it a mandrel.

 

[KnowNothing256]

Unlike an expander ball the entire length of the neck will be on their mandrel style expander at the same time. So I still think it's fair to call it a mandrel.

But not contacting. While the neck is getting sized down, it's on the narrow mandrel section, making no contact; @Baron23 has it right

 

[OREGUN]

Ok, found this pic of mandrel/decapping die combo...and I'm still not sure if I understand. It appears that on the down stroke, it decaps and the bushing compresses neck diameter when the pin/mandrel has the narrow section in the neck (section in the green rectangle)....then on the upstroke, it pulls the mandrel section (red rectangle) through the neck thus opening it back up to the desired I.D.

So, how is this really other than an expander ball with an extended parallel section?

View attachment 8132380

And I note, these decapping pin/mandrel are for the most part out of stock and only come in a couple of diameters per cartridge family?? E.g. image below.

View attachment 8132381
As said, I'm no expert at reloading but I favored having a set of mandrels so I can fine tune my neck I.D. based on exactly how much spring back I'm getting on particular brass. So, I have a 21st Century mandrel die and mandrel kit (see below) and do this as a separate step. Probably overkill (well, def overkill) and I will prob not use the majority of these mandrels....but wow, I'm def set if I need them! hahaha

Mandrel Kit
View attachment 8132395

I think I understand the SAC die...vaguely (haha)...now.

Thanks for your patience in trying to explain to me.

Cheers

I think it’s a geometry thing. Expander balls in traditional dies were, at best, egg shaped. This deal has much shallower tapers and a long section of the chosen diameter. I’m no SAC fanboi. There’s a lot of ways to size a case that are fine. When I was loading for mid range benchrest, I had a finely crafted, many-step process that ensured every piece was EXACTLY the same. I grabbed the SAC die to try as a time saver. I get results from the one hitter die that are exactly the same as from a multi step process using other dies. Every piece has the same shoulder dimensions and neck diameter as though I was doing a two step process. I’m not sure how this is different or better than an “expander ball” but, for me, it is.

I never had a huge collection of mandrel sizes. I typically use one that is .002“ smaller than bullet diameter. I do tend to neck down smaller than some folks...I want the mandrel to positively expand the neck as the last step. So, a bigger neck bushing selection is more important to me than having a bunch of different mandrel sizes to choose from.

My experience has been that for me, mandrelling the neck gives the best consistency but as you see, others have different experiences with that too.

 

[wade2big]

Yup, that's what I do too. I don't even use a mandrel unless there's a reason to on fired brass. I just use my bushing die and that's it. With a correct bushing, a mandrel gave me zero benefit. I tested it with 50 rounds of bushing die and 50 rounds of bushing die + mandrel and the there was no difference at all in accuracy or SD, so I stopped using a mandrel unless I had a dented neck or something.

I use Redding Type S full length bushing dies wih the carbide free floating expander ball installed. I toss the one that comes standard. I use a bushing that sizes the neck down just enough that I lightly feel the expander ball on the upstroke. I get great results doing it this way over multiple cartridges.

Do you just use a bushing to set the final neck tension if you will? Nothing else run through the neck afterwards? Do you neck turn?

 

[Ronc80]

I've had the sac modular sizing die for about a month. I've noticed if you decap while sizing you don't have many options with the mandrel dimension. If you decap before you resize you can get rather custom with the neck size. More size options and it does a petty good job at sizing like it says it is + or - spring back. I use the mighty armory decapper on an old press. Only way to keep my dies and better press clean.
The decapper that came with my full length sizing die is really small. .256 must be more of a universal decapper. I ordered 2 bushings on top of the one that comes with the die and now I have 4 mandrels for 7mm bullet. Bushings .310, .309, .308. Mandrels .2835, .2830, .2825, .2820. Still learning. Had an issue with amp press not having enough set power from factory to fully seat a bullet. Turned it up quit a bit. Still not sure I've worked out my problem. Suppose to be working on it now but it's been a long ass Monday. There's always tomorrow

 

[BuildingConceptsllc]

I use Redding Type S full length bushing dies wih the carbide free floating expander ball installed. I toss the one that comes standard. I use a bushing that sizes the neck down just enough that I lightly feel the expander ball on the upstroke. I get great results doing it this way over multiple cartridges.

Do you just use a bushing to set the final neck tension if you will? Nothing else run through the neck afterwards? Do you neck turn?

Yeah I just use the bushing but that's for MY fired brass. So it's been sizes and fired in my chamber already. I'm not opposed to a mandrel and I obviously have one but when I tested it, there was just zero difference. I have some pretty dang good numbers for SD and ES over a legitimate number of rounds to actually give some credible results, so I just stopped using the mandrel. I like the idea of what you're talking about though.

I use the same dies. Where did you get the mandrel you use?

 

[wade2big]

Yeah I just use the bushing but that's for MY fired brass. So it's been sizes and fired in my chamber already. I'm not opposed to a mandrel and I obviously have one but when I tested it, there was just zero difference. I have some pretty dang good numbers for SD and ES over a legitimate number of rounds to actually give some credible results, so I just stopped using the mandrel. I like the idea of what you're talking about though.

I use the same dies. Where did you get the mandrel you use?

I’ll answer your question but If it ain’t broke, don’t fix it.

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You can find them anywhere that sells the dies. It’s expensive for what it is. The kit comes with the free floating carbide expander, a spare decapping pin, and a little nut to hold it all together. As long as that ball touches the brass, I know I have at least .002” neck tension. Thats what these are under bullet diameter.

 

[BuildingConceptsllc]

I’ll answer your question but If it ain’t broke, don’t fix it.

Carbide Size Button Kits - Redding Reloading Equipment: reloading equipment for rifles, handguns, pistols, revolvers and SAECO bullet casting equipment

Reloading equipment for rifles, handguns, pistols, revolvers, custom dies, bullet casting equipment, powder measuring and weighing equipment, bullet seating dies

www.redding-reloading.com

You can find them anywhere that sells the dies. It’s expensive for what it is. The kit comes with the free floating carbide expander, a spare decapping pin, and a little nut to hold it all together. As long as that ball touches the brass, I know I have at least .002” neck tension. Thats what these are under bullet diameter.

Yeah, I'm a big proponent of "if it ain't broke, don't fix it " too. That ball looks a little different than the others though. If it doesn't need lube it might be good for virgin brass to use the bushing and the ball if it will go up that high. I'd have to play with it to see if that's possible. I think that's basically what the SAC die does but with a precision ground mandrel at the right height to use both?

 

[CK1.0]

After some searching around, it doesn't appear that "sizing die with a mandrel" is really a thing (at least not yet). There are a couple/few companies that call their proprietary expander-ball a "mandrel", and some designs look better than others IMO, but they all work exactly like an expander-ball. I agree with @KnowNothing256, the Lee Collet Die is really the closest thing and that's neck-size-only, so one has to combine that with a body die in a second step.

FWIW, I think guys can make great ammo without using a mandrel die as an added step, especially with a die that uses one of the improved/better expander-ball/faux-mandrel designs over the old style that could really wrench up on the shoulders.

That said, like I mentioned above, now that I've seen just how far out of whack and/or dinged-up freshly-sized necks and case mouths can get when going for a ride in the tumbler to get off all the lube after sizing... I'm going to stick with using a separate mandrel die after. The first time I tried it, I didn't even have to wait to get to the range to see an improvement, one can literally feel how much better and more uniform it makes things when just seating bullets.

 

[OkieMike]

I am just getting in to reloading so I apologize if this is a dumb question.

I am looking for dies for my first reloading press (419 Zero). I like what I see with the SAC sizing dies with the expander mandrels as I have a universal decapping die.

My question is, is there a downside to having the mandrel in the sizing die compared to having a separate expander mandrel die? I am hoping to maximize the cartridges I can reload on each zero tool head. I haven't seen anyone discuss this and maybe that's because I am missing something with my non-existent experience on the subject.

Here's my take on it... And if I'm way out in left field I'm sure the Hide will let me know...

One of the proposed advantages of an expander mandrel die is that it sizes the brass in compression.

When using a sizing die with an expander ball the ball goes through the oversized mouth of the case... The sizing die squeezes the neck/mouth down to undersize. Then when you retract the ram the expander ball sizes the neck on the way out... This is done when the brass is under tension.

When you use a mandrel AFTER the sizing operation you are sizing the neck from the top down when the brass is in compression.

The "theory" being that brass being stronger under compression than it is in tension... You get more consistent results.

So to me, you aren't gaining anything putting an expander mandrel in a sizing die... because you are still sizing the neck as you withdraw the mandrel... when the brass is under tension.

Mike

 

[Mudflap621]

I started with a Forster custom honed die than followed up with a 21st century expander. For ease of use and time saving I purchased the SAC die with decaping mandrel to test.

I have found that my brass is just as consistent as before if not more so.
I also can feel a big difference in the sizing process with the SAC. It’s definitely a more refined die and it’s customizable very easily with different bushing/ mandrel combinations.

I feel way more people have issues with sizing due to improper setup or under lubing their brass.

All in all I’m happy with the SAC die. It’s expensive but it’s consistency and time savings are worth it for me.

 

[Mudflap621]

I feel that most factory sizing dies size the neck way too small to begin with. Now you’re pulling an expander out of it with too much tension which creates inconsistency.

If your only working brass a couple thousandths I haven’t see a difference personally.

 

[pshell]

Here's my take on it... And if I'm way out in left field I'm sure the Hide will let me know...

One of the proposed advantages of an expander mandrel die is that it sizes the brass in compression.

When using a sizing die with an expander ball the ball goes through the oversized mouth of the case... The sizing die squeezes the neck/mouth down to undersize. Then when you retract the ram the expander ball sizes the neck on the way out... This is done when the brass is under tension.

When you use a mandrel AFTER the sizing operation you are sizing the neck from the top down when the brass is in compression.

The "theory" being that brass being stronger under compression than it is in tension... You get more consistent results.

So to me, you aren't gaining anything putting an expander mandrel in a sizing die... because you are still sizing the neck as you withdraw the mandrel... when the brass is under tension.

Mike

^ one of the reasons I switched.
I haven't verified this, but I've also read the under-tension technique potentially contributes to increasing brass length. The idea that I could reduce the need to trim was enough for me to switch from the one-die with Redding carbide ball to a dedicated die.
Low double-digit SDs became single-digit SDs once I switched, and the seating feel was more consistent. I haven't tested the brass growth theory.

 

[kthomas]

I've had really good luck with Whidden FL sizers with the expander ball. I personally haven't seen the need to dedicate a step for just a mandrel.

Single digit SD's (3-6 depend on the cartridge, a 34 shot string with my 6BRA had an SD of 4.1) and ammo that could put up an honest 5x5 that averages under 1/3 MOA.

I would be curious to see what I could gain by going to a dedicated mandrel, would be interesting to see if there is a perceivable performance difference.

 

[OREGUN]

I've had really good luck with Whidden FL sizers with the expander ball. I personally haven't seen the need to dedicate a step for just a mandrel.

Single digit SD's (3-6 depend on the cartridge, a 34 shot string with my 6BRA had an SD of 4.1) and ammo that could put up an honest 5x5 that averages under 1/3 MOA.

I would be curious to see what I could gain by going to a dedicated mandrel, would be interesting to see if there is a perceivable performance difference.

I often wonder if the “you must mandrel for consistent neck tension” ethos isn’t a bit of old-timey reloading myth. I don’t think it always matters exactly what you do but rather that you do the exact same thing to every case. So if the ex-ball gives you consistent results you probably can’t beat it by mandrelling. Hard to beat single digit SDs over 34 shots.

 

[Stevo86]

Lee collet die w/ redding body die… all ya need

Edit: I do use a mandrel on my 25 creedmoor, it is nice to be able to control the ID neck tension, with the lee die you’ll have to order a undersized mandrel

 

[Dil pickle]

This might be a dumb question, but being the sac die does it all in one stroke, I’ve been that(decap,size,mandrel) then tumbling.
Most dies nowadays decap and size in one stroke, so does this mean they’re promoting sizing prior to cleaning? This is how I’ve been doing it. Seems to be okay, my brass doesn’t even touch the ground.

Or are people just tumbling with primers in, then doing the whole sizing process after? Can’t imagine it makes a difference, my brass has only a tiny bit of carbon on the necks.

 

[kthomas]

This might be a dumb question, but being the sac die does it all in one stroke, I’ve been that(decap,size,mandrel) then tumbling.
Most dies nowadays decap and size in one stroke, so does this mean they’re promoting sizing prior to cleaning? This is how I’ve been doing it. Seems to be okay, my brass doesn’t even touch the ground.

Or are people just tumbling with primers in, then doing the whole sizing process after? Can’t imagine it makes a difference, my brass has only a tiny bit of carbon on the necks.

Tumble with primers in

 

[TheOfficeT-Rex]

I wouldn't recommend wet tumbling before decapping - water tends to stay in the base of the case and take longer to dry in my experience.

 

[rookie7]

Lee collet die w/ redding body die… all ya need

Edit: I do use a mandrel on my 25 creedmoor, it is nice to be able to control the ID neck tension, with the lee die you’ll have to order a undersized mandrel

Redding body die with bushing to control how much the neck is sized down? Or just a plain sizing die? thanks

 

[Stevo86]

Just a body sizing die, doesn’t touch the neck. Guess u could use a type s bushing die as well and leave the bushing out