Do you use expanding mandrels after a full-length bushing die for neck sizing?

[Rio Precision Gunworks]

I suppose that whole thing could be but only that little bit actually works the brass. Looks more like an expander ball though in that it drags on its way out.

Most mandrels look like this
View attachment 8316635
Flat on top that reference against the dies flat top to keep it plumb as it’s forcing it’s way down into the case mouth opening it up to the cylinder diameter.

I've avoided talking about "mandrels" like SAC and 418 as they aren't one long bearing surface. They are thinner above the "mandrel" part. So, they have a long bearing surface that contacts the inside of the neck, but they are only doing so on the upstroke like an expander ball.

I haven't given much thought to why one is better than the other, so avoided getting into the conversation. But it's interesting.

 

[FNG1001]

I suppose that whole thing could be but only that little bit actually works the brass. Looks more like an expander ball though in that it drags on its way out.

Most mandrels look like this
View attachment 8316635
Flat on top that reference against the dies flat top to keep it plumb as it’s forcing it’s way down into the case mouth opening it up to the cylinder diameter.

Yes agreed. Just curious what others thought about the Bullet Central mandrel. I too thought they looked and a lot like expander balls. So the discussion of using a mandrel vs expander ball can get nebulous depending on the definition of either.

I've avoided talking about "mandrels" like SAC and 418 as they aren't one long bearing surface. They are thinner above the "mandrel" part. So, they have a long bearing surface that contacts the inside of the neck, but they are only doing so on the upstroke like an expander ball.

I haven't given much thought to why one is better than the other, so avoided getting into the conversation. But it's interesting.

 

[Rio Precision Gunworks]

Yes agreed. Just curious what others thought about the Bullet Central mandrel. I too thought they looked and a lot like expander balls. So the discussion of using a mandrel vs expander ball can get nebulous depending on the definition of either.

I think the "definition" would likely hinge on something measurable like shoulder movement and/or concentricity.

If the expander ball's cons are that it can stretch the should back and/or not be as concentric, then you would define a mandrel as anything that gives the desired ID/uniformity without changing dimensions that you want to keep.

 

[memilanuk]

When did everyone transition from bushing dies to mandrel? It seems like it’s all a new rave and I missed the invitation to the party

About ten years ago, in F-class. Dunno when it caught on in the PRS crowd.

 

[Rio Precision Gunworks]

About ten years ago, in F-class. Dunno when it caught on in the PRS crowd.

I think around five years ago for PRS types. I know for sure it wasn't extremely rare then for PRS.

Probably took a couple years to really catch on. Similar to Neolube. We were using that several years ago, and it's now starting to become more mainstream.

 

[ECK]

I got into loading for PRS back in 2017, back then IIRC neck sizing or shoulder bump sizing was the preferred. Came back to it in 2022 and seemed like it swung back to FL sizing.

Now I’m FL sizing and running a mandrel to set the neck ID. I’m still running sizers with bushings in them, but I feel like the mandrel resulted in more consistency based on results I’m getting down range.

 

[RUN8]

I think the "definition" would likely hinge on something measurable like shoulder movement and/or concentricity.

If the expander ball's cons are that it can stretch the should back and/or not be as concentric, then you would define a mandrel as anything that gives the desired ID/uniformity without changing dimensions that you want to keep.

Data point of 1, but my shoulder measurements didn’t change between brass resized in the SAC full length resizing die before and after I installed the optional carbide mandrel. Maintained the .002” shoulder bump from the original pre-mandrel setup.

The .2610” bearing surface of the mandrel is near enough to .540” in length, so the full case neck is supported as the case is removed from the die and the transition is supposed to be immediate from coming out of the neck/shoulder bushing so it hands off with no room to become misaligned.

 

[Yondering]

I think the "definition" would likely hinge on something measurable like shoulder movement and/or concentricity.

If the expander ball's cons are that it can stretch the should back and/or not be as concentric, then you would define a mandrel as anything that gives the desired ID/uniformity without changing dimensions that you want to keep.

Hmm. It’d be odd and very nebulous to define a specific part shape by the end result of a variable process.

Keep it simple: by the definition everyone here uses, a mandrel is a straight shaft that expands the neck as it’s pushed into the case, forcing the case neck to align with the straight shaft.

An expander ball has a bulged section that typically expands when extracted through the case neck, generally being used inside a sizing die.

 

[Yondering]

Date point of 1, but my shoulder measurements didn’t change between brass resized in the SAC full length resizing die before and after I installed the optional carbide mandrel. Maintained the .002” shoulder bump from the original pre-mandrel setup.

The .2610” bearing surface of the mandrel is near enough to .540” in length, so the full case neck is supported as the case is removed from the die and the transition is supposed to be immediate from coming out of the neck/shoulder bushing so it hands off with no room to become misaligned.View attachment 8316827

Despite how many people promote mandrels here as the ultimate neck expanding mechanism, I’ve had very good results with carbide expander balls too, as long as they are sized correctly.

I lube case necks though, and the combination of lube and slick carbide means no shoulder movement when extracting the case.

 

[RegionRat]

If you're talking group size out to a few hundred yards or less, you will likely see little difference (or, at least, most people can't take advantage of the gain). If you're talking really stretching things out, then SDs start to matter.

I did a fair amount of SD testing comparing using neck lube (or not) and using a mandrel (or not) and various permutations between the two. There is definitely a correlation between these variables and variability in seating force. There is then a correlation between variability in seating force and SDs of fired rounds.

I've gone down the rabbit hole of testing different neck lubes and brass conditions. I think I'm now stuck in said rabbit hole

Here is the thread I started on this whole subject:

Mandrel Musings

When I first got my K&M arbor press for seating, I was somewhat surprised at the spread of the values of force required to seat bullets. Knowing that neck tension plays a significant role in ES/SD, I started doing various things to try to bring seating force in line. I had been doing most my...

www.snipershide.com

I forgot to mention I looked at your previous thread and studied/plotted your data. When you look at it, there is a benefit to controlling your seating force, but also to keeping the variation to a minimum.

For the gas and magazine folks who are trying to raise the average seating force to make sturdy ammo, work like Rocketmandb is not in hand to show what happens if you try for a higher seating force average.

In general, you have a harder time controlling that variation as the seat force average goes up, and we don't have enough public data to see if that extra case prep work will yield good performance in terms of SD/ES values as in when those loads are taken to distance.

This first plot shows there is a strong couple between prepping for higher seating forces and getting more dispersion in the results. The caveat in this example is that there were differences in how and why the average seating force was achieved. There were significant differences in friction coefficient. To be fair, we would need to use the same friction coefficient treatment and then vary the interference, however, previous unpublished testing of this has shown the same general relationship will result. Higher seating forces are challenging to manage in terms of variation.

That next question comes up and since the above results have the variation "baked-in" and Rocketmandb was kind enough to share his chrono results, we can show a fair correlation that justifies the effort. When you control the variation in your brass prep, you get tighter velocity SD/ES.

The theory is that these issues have a stronger influence on the part of the trajectory that is typically out past 300 yards and more often out past 500 yards. It takes that far before the vertical contribution from pure velocity variation is something that can hurt you. In all his results, these standard deviation values are in a class that would not hold you back in a MidRange Match.

The next hard question becomes... can a brass prep method give you complete control of seating force, and will that method give you control over the StD of that seating force so that you can make that seating force as high or low as you wish without penalty on the target.

Credits to Rocketmandb for sharing his hard work. Carry on.

Happy New Year.

 

[Rocketmandb]

Higher seating forces are challenging to manage in terms of variation.

While I generally agree with this statement, the data from my other thread is necessarily not a valid sample to justify the statement. The reason being that the higher seating forces were caused by two things:

- No lube used
- No mandrel used
(or both)

In the both cases, you'd expect higher variability, but the causal factor is not higher seating force. In the case of lube vs no lube, lubricant evens out the coefficient of friction, so no lube means higher variability and higher seating force. In the case of no mandrel, you get higher seating force because the interference fit is tighter, and you get higher variability because of differences in neck thickness.

To appropriately test how much a higher seating force impacts variability, an appropriate test would be to use the same method for lube and mandrel, but use progressively smaller mandrels and then measure both the seating forces and variability.

Fun test - after I get my 3 new barrels broken in and load dev done, I might have to play there.

 

[blksno]

A couple things to unpack here:

- If you're deforming tips, the problem is the seating stem, not the annealing. The tip should never touch the stem; you'll want to either buy the correct stem to match that bullet, or modify the one you have. There are several methods for that - lapping the stem to the bullet profile, bedding with epoxy, etc. If the stem is touching the tip though the first step is to drill the center hole deeper - if the tip is touching then it'll introduce variations in seating depth when measured to the ogive.

- If you need to anneal twice, then your initial annealing isn't hot enough or long enough; it's not doing its job. More work does not equal better results, just get that initial annealing set up better and you can skip doing it a second time.

The deformation is not in the very tip...I use the term "tip" as any portion of the jacket forward of the ogive. I got a custom stem for 143 Eldx and its less pronounced but didn't fix the issue.

As I said...the 2nd pass isn't important for seating...but I can absolutely feel the difference running the press. Almost like the first step has .0005 spring back because the brass has cooled. I don't care at all if I have .001 of neck tension before. And .001 of neck tension after. It's more consistent with this case and bullet.

I don't use this process for any of the other dozen or so cases I load for. Never needed to.

 

[RegionRat]

To appropriately test how much a higher seating force impacts variability, an appropriate test would be to use the same method for lube and mandrel, but use progressively smaller mandrels and then measure both the seating forces and variability.

Yes, very much agree.

The work isn't published but in general: for an identical average, with-lube is better than without-lube due to smaller variation.
However, you will still see the similar outcome in terms of the dispersion increasing with a higher average force, regardless of lubrication.
That is just the cruelty of tribology and mother nature.

We see this with threaded fastener testing when measurements of various types of Loctite or "lubrication" is applied. Some forms of Loctite are supposed to be lubricants but they actually have a higher friction coefficient than "dry naked", however, we still adopt them from a simple view of how much smaller the dispersion is when they are used. We may have to apply higher torque to get the same tension force, but because the results are more reliable, we run them.

A good demo would be that test with all other things being equal... does no-turn versus turn show up as extra seating force variation?

Aside from the question at hand in terms of mandrels versus other prep methods, it is a fair amount of tedious work and expense to turn necks.

Many serious shooters have jumped back and forth between the two camps and it is difficult to sort out how much credit should be given to neck thickness variation.

Again, very nice work in your old thread.

Happy New Year!

 

[Rio Precision Gunworks]

Hmm. It’d be odd and very nebulous to define a specific part shape by the end result of a variable process.

Keep it simple: by the definition everyone here uses, a mandrel is a straight shaft that expands the neck as it’s pushed into the case, forcing the case neck to align with the straight shaft.

An expander ball has a bulged section that typically expands when extracted through the case neck, generally being used inside a sizing die.

Yea, it wouldn't be a good idea to define the part. You'd want to define the intent and then listed the tools that will achieve that.

Was not a good explanation on my part.

 

[Haney]

Smart Reloading — Use Expander Mandrels with New Brass « Daily Bulletin

Before you load that nice new cartridge brass for the first time, run an expander mandrel down the case necks. This will iron out dents and provide more uniform neck tension. Chose a mandrel diameter that provides appropriate neck tension.

bulletin.accurateshooter.com

 

[morganlamprecht]

Sounds like you need better bullets, if they deform under as little as 2 thou neck tension.

When I tested neck prep/tensions years ago to find where I wanted to settle my process, the actual size of the neck mattered FAR less than inside neck surface finish

On my hydro press, leaving the neck in a less than ideal state it would yield 90-100+ PSI even with only .001-.002 thou of interference and it would ring some bullet brands on the ogive

Those same bullets would seat fine with 20-40 psi and .002-.004 interference with what I consider proper neck conditions for seating

Just food for thought

 

[memilanuk]

Fair enough. I'd sure test things like brushing the neck ID and/or lubing the necks before I'd re-anneal or run 1 thou NT.

 

[Rio Precision Gunworks]

Have also observed the same. From things as small as excessive friction.

Take virgin alpha that has similar neck thickness and inside diameter as other brands and you’ll get a much higher seating force and in turn more surface damage (some is likely just cosmetic, but not all) on the bullet.

The inside of the necks “looks” cleaner than other. I’m sure it’s not just as simple as clean, but that’s how it looks to the naked eye.

Lube or even just running a mandrel (but not changing the ID) takes the seating pressure way down and alleviates jacket damage.

And it’s only with virgin Alpha brass. Subsequent firings are “normal.”

 

[morganlamprecht]

Fair enough. I'd sure test things like brushing the neck ID and/or lubing the necks before I'd re-anneal or run 1 thou NT.

Same…noticing the higher seating forces on what should have been very little interference is what lead to me pay more attention to the inside surface in the first place, accidental find

 

[RUN8]

Have also observed the same. From things as small as excessive friction.

Take virgin alpha that has similar neck thickness and inside diameter as other brands and you’ll get a much higher seating force and in turn more surface damage (some is likely just cosmetic, but not all) on the bullet.

The inside of the necks “looks” cleaner than other. I’m sure it’s not just as simple as clean, but that’s how it looks to the naked eye.

Lube or even just running a mandrel (but not changing the ID) takes the seating pressure way down and alleviates jacket damage.

And it’s only with virgin Alpha brass. Subsequent firings are “normal.”

Don’t the instructions from Alpha include running a mandrel through their virgin brass prior to loading?

I plan to anyway just to make sure there aren’t any dents in the 100 pieces I just got from them.

 

[secondofangle2]

I actually emailed Peterson about six or seven years ago about their 260 Remington brass, because the seating force was off the charts, and it was due to friction inside the necks with virgin brass

They never acknowledged it, but I knew what was going on, and like above, it went away on subsequent firings

 

[Rio Precision Gunworks]

Don’t the instructions from Alpha include running a mandrel through their virgin brass prior to loading?

I plan to anyway just to make sure there aren’t any dents in the 100 pieces I just got from them.

I'll have to check. There's a ton of people on social media who promote a "just pull it out the box and load it." Since we sell a lot of Alpha brass we try to have experience in any common way people might go about it. If nothing else, to be able to answer customer questions.

But, agreed. It's always a good idea to run a mandrel for several reasons.

 

[memilanuk]

Seating force on virgin Lapua was always stupid high. More than once I'd heard that tumbling in dirty media would smooth it out. Even from the Lapua rep at Southwest Nationals. Little bit of tumbler dust to lube things up goes a long ways.

 

[DeathBeforeDismount]

Have also observed the same. From things as small as excessive friction.

Take virgin alpha that has similar neck thickness and inside diameter as other brands and you’ll get a much higher seating force and in turn more surface damage (some is likely just cosmetic, but not all) on the bullet.

The inside of the necks “looks” cleaner than other. I’m sure it’s not just as simple as clean, but that’s how it looks to the naked eye.

Lube or even just running a mandrel (but not changing the ID) takes the seating pressure way down and alleviates jacket damage.

And it’s only with virgin Alpha brass. Subsequent firings are “normal.”

That's one of the reasons I don't use SS pins and only wet tumble for 15-20 minutes.

No my brass doesn't get extra shiney but it leaves hard carbon residue inside the cases. Not enough to make a pressure difference but it acts as lube for the mandrel and i get much more consistent neck tension.

My SD/ES shrink almost in half from virgin to once fired. I hypothesize its part of the reason why. All i do with virgin brass is mandrel to fix the casemouths since they tend to get dinged when bulk stored.

 

[DeathBeforeDismount]

Seating force on virgin Lapua was always stupid high. More than once I'd heard that tumbling in dirty media would smooth it out. Even from the Lapua rep at Southwest Nationals. Little bit of tumbler dust to lube things up goes a long ways.

I think its a combination of undersized case mouth and no lube.

Bush sizing down .002-3 then back up .002 under bullet diameter with a mandrel plus the added "lube" from carbon makes seating very smooth with about .001-.002 neck tension accounting for springback.

 

[232593]

IMO that is because until relatively recently the only ones using mandrels outside of forming a wildcat were those who participate in shooting disciplines that single load. Those who use magazines or a semi-auto may desire more grip on the bullet.

Especially an AR10 in 22CM with the 90 grain bullets.

 

[Chris1972]

A mandrel does not dictate low neck tension. I see lots of talk about .001-.002 bring your options. SAC mandrels offer up to .004” on most calibers.

 

[Western Living]

OP here. I ended up buying the LE Wilson expanding die and mandrel for 6.5mm. It expands my brass to 1 thou under or .263" ID - the same as the OD of the mandrel itself. That is not enough neck hold. I can push a bullet in or pull it out with my fingers. To be clear: I resize the neck with a bushing die so that it is fairly small -- 3 thou under. Then I open the neck with the LE Wilson expanding mandrel, and it is too loose.

So this expanding mandrel is worthless to me. The die may still have potential. I paid $50 for it with the mandrel, so I'm not out too much. It looks like now I need a neck-turning mandrel that would be 2 thou under and I believe most of the brands are compatible. So, if I get a .262" mandrel, I should be in-business.

Are there other mandrels compatible with the LE Wilson die? Because it looks like the Wilson mandrel has male threads on it and the others look like they do not.

 

[CheapBasterd]

OP here. I ended up buying the LE Wilson expanding die and mandrel for 6.5mm. It expands my brass to 1 thou under or .263" ID - the same as the OD of the mandrel itself. That is not enough neck hold. I can push a bullet in or pull it out with my fingers. To be clear: I resize the neck with a bushing die so that it is fairly small -- 3 thou under. Then I open the neck with the LE Wilson expanding mandrel, and it is too loose.

So this expanding mandrel is worthless to me. The die may still have potential. I paid $50 for it with the mandrel, so I'm not out too much. It looks like now I need a neck-turning mandrel that would be 2 thou under and I believe most of the brands are compatible. So, if I get a .262" mandrel, I should be in-business.

Are there other mandrels compatible with the LE Wilson die? Because it looks like the Wilson mandrel has male threads on it and the others look like they do not.

What kind of brass? how many times fired? Annealed?
Just wondering because .263 seems to be the default standard in some of these kits. I just got the 21st century die with .263 and I cant push/pull these bullets with my fingers. This in non-annealed 1 x fired brass. Sized with a Forster FL die with the expander removed. I ended up with .003 "tension"

 

[Yondering]

OP here. I ended up buying the LE Wilson expanding die and mandrel for 6.5mm. It expands my brass to 1 thou under or .263" ID - the same as the OD of the mandrel itself. That is not enough neck hold. I can push a bullet in or pull it out with my fingers. To be clear: I resize the neck with a bushing die so that it is fairly small -- 3 thou under. Then I open the neck with the LE Wilson expanding mandrel, and it is too loose.

So this expanding mandrel is worthless to me. The die may still have potential. I paid $50 for it with the mandrel, so I'm not out too much. It looks like now I need a neck-turning mandrel that would be 2 thou under and I believe most of the brands are compatible. So, if I get a .262" mandrel, I should be in-business.

Are there other mandrels compatible with the LE Wilson die? Because it looks like the Wilson mandrel has male threads on it and the others look like they do not.

You may be stuck with Wilson mandrels for that die; not sure. Several of us here recommended mandrels from SAC or 21st Century among others, which all use a common mandrel type so there are more options.

If you can push a .264” bullet in and out by hand, the neck isn’t .263”; it’ll be closer to .264” with maybe a few ten thousandths tension.

 

[Chris1972]

Are you sure your bushing is giving the tension you think it is. .003”. I’m not doubting you but there may be more spring back there than you are aware of. Obviously if you’ve used this same bushing before the mandrel you know what’s going on with it already.

 

[HerCoStarNTheBeaverPictur]

How do you get a 002 under mandrel from Sinclair? They say theirs are 1 under. You use their neck turning mandrel? Or from 21st? You bought the kit or the ones sold in half-thou increments?

26 Hollands Solid Carbide Expander Mandrel - Sold Individually

Sizes 6mm. 6.5 mm 7mm and 308 All Mandrels precision ground to provide precise .002 neck tension when used properly. Mandrels fit Sinclair die holder or use HOLLANDS IMPROVED DIE BODY. Mandrels $25 each or set of 4 for $90

www.hollandguns.com

 

[CK1.0]

After FL sizing and then tumbling off all the sizing lube first... I like/use the Sinclair mandrel dies with one of their "turning arbors" (.002" under bullet OD). Tumbling off the lube before hitting the mandrel actually does seem to matter, as the mandrel "fixes up" some of the minor damage the tumbling causes to case necks/mouths with them crashing into each other while tumbling.

I've moved towards using regular FL dies or custom-honed FL dies instead of bushing dies, but I think bushing dies work fine too as long as one squashes the necks down enough (for me that means .266" for 6mm before opening it up with a .241" "turning arbor").

I think all of the dies that claim they mandrel at the same time they size ala A419, SAC, Mighty Armory, etc are all BS. If they did the same exact thing as what an FL die followed by a legit mandrel does, then every single case would get stuck, as the "magic" lies in the overlapping dimensions (squash a bit too much, then open them back up)... IMO it's just marketing nonsense, there's no such thing as free lunch.

Of course, I anneal every firing and use Alpha and/or Lapua brass all from the same lots... and unless one does too, they may never see a benefit or notice any difference employing a mandrel.

 

[Chris1972]

CK1.0 one of us does not understand the SAC die.

The Mandrel goes freely through the neck of the unsized brass and the top of the mandrel is a smaller dimension allowing the shoulder/neck bushing to set the neck tension tight. Then on the upstroke (of the handle) the mandrel opens the neck up to the desired size. It actually works very well. My bushing sets .003” and my mandrel is .0025”.

 

[FNG1001]

After FL sizing and then tumbling off all the sizing lube first... I like/use the Sinclair mandrel dies with one of their "turning arbors" (.002" under bullet OD). Tumbling off the lube before hitting the mandrel actually does seem to matter, as the mandrel "fixes up" some of the minor damage the tumbling causes to case necks/mouths with them crashing into each other while tumbling.

I've moved towards using regular FL dies or custom-honed FL dies instead of bushing dies, but I think bushing dies work fine too as long as one squashes the necks down enough (for me that means .266" for 6mm before opening it up with a .241" "turning arbor").

I think all of the dies that claim they mandrel at the same time they size ala A419, SAC, Mighty Armory, etc are all BS. If they did the same exact thing as what an FL die followed by a legit mandrel does, then every single case would get stuck, as the "magic" lies in the overlapping dimensions (squash a bit too much, then open them back up)... IMO it's just marketing nonsense, there's no such thing as free lunch.

Of course, I anneal every firing and use Alpha and/or Lapua brass all from the same lots... and unless one does too, they may never see a benefit or notice any difference employing a mandrel.

Micron Precision is another that advertises their dies as bushing+mandrels in 1.

 

[CK1.0]

CK1.0 one of us does not understand the SAC die.

The Mandrel goes freely through the neck of the unsized brass and the top of the mandrel is a smaller dimension allowing the shoulder/neck bushing to set the neck tension tight. Then on the upstroke (of the handle) the mandrel opens the neck up to the desired size. It actually works very well. My bushing sets .003” and my mandrel is .0025”.

You’re right about one of us not understanding lol…

What you describe may indeed be a better execution of doing what an expander ball does… but it’s not the same thing as what a mandrel does.

Pushing down into the necks with the case’s shoulder supporting itself most effectively to remain unchanged, versus pulling up through the shoulder where it’s weaker and can more easily distort, is the whole enchilada as they say.

 

[Chris1972]

I see your point. I didn’t consider that it may distort the shoulder from the pulling effect. I never thought about that with an expander ball either since that’s always just been the way. For me the mandrel is for concentricity. Less run out and consistent neck tension.

 

[Cardboard Assassin]

You’re right about one of us not understanding lol…

What you describe may indeed be a better execution of doing what an expander ball does… but it’s not the same thing as what a mandrel does.

Pushing down into the necks with the case’s shoulder supporting itself most effectively to remain unchanged, versus pulling up through the shoulder where it’s weaker and can more easily distort, is the whole enchilada as they say.

This is the way I see it too.

Part of the attraction of a mandrel is that you are pushing it into the neck and as this is the way that should be strongest / distort the neck the least it should yield the best results.

I guess a mandrel being dragged back through the neck might be better than an expander ball (longer surface should make it more uniform) but I'll keep on with the expander mandrel being pushed in as my results have been great.

 

[Rio Precision Gunworks]

SAC and Area419 are both using pull through mandrels (that's probably the best name for them).

Currently I'm not sure if suffer from the same downfalls as expander balls. I'm hoping they both realized it was the same motion of expander ball and they checked to make sure it didn't do the same thing.

 

[Yondering]

SAC and Area419 are both using pull through mandrels (that's probably the best name for them).

Currently I'm not sure if suffer from the same downfalls as expander balls. I'm hoping they both realized it was the same motion of expander ball and they checked to make sure it didn't do the same thing.

Or they just know that marketing terms sell? Maybe I'm just cynical but I suspect that's closer to the full truth.

JMHO but I'll take a carbide expander ball over a pull through mandrel any day. Slick and less surface area = less shoulder/neck distortion.

 

[Yondering]

I see your point. I didn’t consider that it may distort the shoulder from the pulling effect. I never thought about that with an expander ball either since that’s always just been the way. For me the mandrel is for concentricity. Less run out and consistent neck tension.

The shoulder support when pushing into the case neck is pretty much the whole point of a mandrel. That is how they produce (at least in theory) less runout.

Although as I mentioned earlier in the thread, carbide expander balls in a bushing die (that's not sizing down too much) also gives very good results, especially with lubed necks. But you can feel a dramatic difference at the press handle between that and a conventional FL die with a steel expander ball. Lower extraction force results in less chance of shoulder distortion, and there's a minimum value below which there is no permanent distortion.

As a side note when using mandrels now, I like to use some variation of the Lyman M-die style, adjusted for a small portion of the case neck to be full bullet diameter. It seems to help with concentric seating, eliminates the need for inside neck chamfers, and if loading on a progressive with a bullet feeder it speeds things along considerably.

 

[Chris1972]

I guess I’m going to have to do some testing with my SAC with and without the mandrel and take some measurements. I had no idea this theory existed and feel almost no resistance when I pull the mandrel out of the brass. Never too old to learn.

 

[Cynical]

Or they just know that marketing terms sell? Maybe I'm just cynical but I suspect that's closer to the full truth.

JMHO but I'll take a carbide expander ball over a pull through mandrel any day. Slick and less surface area = less shoulder/neck distortion.

SAC has a carbide mandrel available for the modular dies, still pull through though if that hurts anyone’s feelings too much.

 

[BuildingConceptsllc]

Does anyone have any actual tests that showed there's a difference in pulling the mandrel through vs pushing it through?

 

[Rio Precision Gunworks]

Does anyone have any actual tests that showed there's a difference in pulling the mandrel through vs pushing it through?

Paging @Rocketmandb

If you don't have this info, new test maybe?

 

[morganlamprecht]

Does anyone have any actual tests that showed there's a difference in pulling the mandrel through vs pushing it through?

i dont have pulling vs pushing, but best i got...

years ago i loaded 50 rounds each with...

redding bushing die w/ the expander ball in
redding bushing die w/ expander ball removed, then pushing mandrel thru it (conventional fashion)
cheap ass standard lee die

lapua brass/berger 140 bt target/cci450/h4350

other than the dies being different, i used all my normal brass prep/load steps

i went and shot them at 800 in 10 shot groups...and after like 3-10 shot groups of each at 800...all the groups being in the 1/2moa-3/4moa range w/ no particular batch consistently better, and with similar numbers on the labradar...i quit before i wasted the rest of the rounds, saw what i needed to see

1/2moa - 3/4moa was the normal variation id already seen shooting 800 w/ that rifle and using all the same loaded ammo with no changes made

my take away was....yes, you could likely make bad ammo from improper use or understanding of a die/tool/reloading steps...and maybe switching to a different type of die "fixes" someones problem, but maybe it fixed it because of a reason they weren't aware of, not only because of the die/method itself

but if your process was squared away, and gets to a similar loaded round...the die used didnt matter for me

if i was going to test the dies further, id need either better equipment or a better shooter

none of my 3 die setups created crazy amounts of run out or inconsistency with loaded rounds though....maybe some out there do, but to me that is more of a die or brass quality/manufacturing problem than the type of die method

maybe id see a difference shooting paper for score over and over for extended periods of time and a much larger sample, but that wasnt my game and not my concern at the time

 

[Rocketmandb]

Paging @Rocketmandb

If you don't have this info, new test maybe?

I'd have to find expander balls for my dies...

 

[Rocketmandb]

Also, literally every rifle I own is at Spartan Precision getting new barrels fitted (in one case, chamber adjusted). I was supposed to drive up to Idaho, watch and learn while I was there as Marc cut the barrels, and drive back with four rifles all set with new barrels/chamber ready for barrel break-in and load development (all barrels are slightly different than the previous).

Unfortunately, a combination of stupidity (mine), a storm cutting through the Sierras on the front end, a storm blowing across Idaho on the other end, and a business trip requiring me to be in Florida meant that I got up there (late) and left with no rifles. I have to go back up either next week or the week after (weather permitting).

In short, I have to 1) get my rifles complete and back, 2) speed the barrels up, 3) do some load dev.

EDIT: which means little to no testing for the foreseeable future

EDIT 2: well... maybe. My 308 is just getting the chamber altered a little, meaning I can use the same brass I've been using, etc. (when I get the rifle back) - AND - I've got nothing else rifle-related to do for at least a week, probably 2 (again, weather permitting).

Key issues:

- You want to measure to the shoulder and the overall length for both.
- This means starting length needs to be the same
- I'd want to sort out brass that currently all has the same length to begin with. I trim every go, so this shouldn't be an issue.
- Measurements: base to shoulder using LE Wilson gauge, overall length, pin gauge after sizing, and for shits and giggles, seating force consistency, though the pin gauge should give the indicator of that.

Process:

- Two sets of brass - Set 1: mandrel - Set 2: expander ball
- Set 1: Size (no expander), mandrel, measure, trim, prime, charge, seat (AMP Press)
- Set 2: Size (expander), no mandrel, all else the same

The only thing I can think of that would be slightly different would be the lube for the mandrel. Perhaps I lube up the mandrel and expander ball both - or - (I'm a fucking masochist) do three sets where the expander ball is both lubed every 5 rounds or so and not.

 

[Yondering]

Also, literally every rifle I own is at Spartan Precision getting new barrels fitted (in one case, chamber adjusted). I was supposed to drive up to Idaho, watch and learn while I was there as Marc cut the barrels, and drive back with four rifles all set with new barrels/chamber ready for barrel break-in and load development (all barrels are slightly different than the previous).

Unfortunately, a combination of stupidity (mine), a storm cutting through the Sierras on the front end, a storm blowing across Idaho on the other end, and a business trip requiring me to be in Florida meant that I got up there (late) and left with no rifles. I have to go back up either next week or the week after (weather permitting).

In short, I have to 1) get my rifles complete and back, 2) speed the barrels up, 3) do some load dev.

EDIT: which means little to no testing for the foreseeable future

EDIT 2: well... maybe. My 308 is just getting the chamber altered a little, meaning I can use the same brass I've been using, etc. (when I get the rifle back) - AND - I've got nothing else rifle-related to do for at least a week, probably 2 (again, weather permitting).

Key issues:

- You want to measure to the shoulder and the overall length for both.
- This means starting length needs to be the same
- I'd want to sort out brass that currently all has the same length to begin with. I trim every go, so this shouldn't be an issue.
- Measurements: base to shoulder using LE Wilson gauge, overall length, pin gauge after sizing, and for shits and giggles, seating force consistency, though the pin gauge should give the indicator of that.

Process:

- Two sets of brass - Set 1: mandrel - Set 2: expander ball
- Set 1: Size (no expander), mandrel, measure, trim, prime, charge, seat (AMP Press)
- Set 2: Size (expander), no mandrel, all else the same

The only thing I can think of that would be slightly different would be the lube for the mandrel. Perhaps I lube up the mandrel and expander ball both - or - (I'm a fucking masochist) do three sets where the expander ball is both lubed every 5 rounds or so and not.

My takeaway from all this was: You only have 4 rifles?

 

[Rio Precision Gunworks]

I'd have to find expander balls for my dies...

Do you think you'd see a difference in pull through mandrels and expander balls? Or pull though mandrels and push through mandrels?