Do you skip the expander mandrel?

[Revolting Peasant]

Another good solution here is Neolube No.2.


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Q Tip or how do you apply?

 

[Lawnboi]

I messed with graphite lube a lot. Redding makes a ceramic bead/graphite combo that you can dip your necks in.

Once I started annealing I really noticed that the graphite just wasn’t doing it. I’d gall mandrels, and stick brass to them with using just graphite. And that’s including some carbon in the neck from dry tumbling.

Once I swapped over to a wet lube, personally I use imperial, wipes on the rim after lubing the body, things got alot more consistent in regards to mandrel use. The galling/sticking went away. But then it requires another tumble.

 

[Mulyhuntr]

I use a mandrel because I don't neck turn.

 

[Mike D Texas]

Q Tip or how do you apply?

Yep I buy “q tips” in bulk on Amazon but with foam heads instead of cotton.

No stray fibers.


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[SloppyJ]

I'm pretty new, only been doing it a year or so but I've had great luck bumping shoulders with my FL sizing die with the mandrel in it. To me this is a KISS kind of philosophy and it's been working great.

I get a little confused when people run mandrels by themselves. At that point what's the difference between that and using a FL sizing die? Other than you can get the mandrels at different ODs.

 

[Harvey_NW]

I'm pretty new, only been doing it a year or so but I've had great luck bumping shoulders with my FL sizing die with the mandrel in it. To me this is a KISS kind of philosophy and it's been working great.

I get a little confused when people run mandrels by themselves. At that point what's the difference between that and using a FL sizing die? Other than you can get the mandrels at different ODs.

It's known that expander balls in a standard FL sizing die can induce runout, however I don't think runout effects the precision as much as people believe it does. I would bet that in most cases a minor amount of runout vs perfectly concentric ammo wouldn't shoot a measurable difference in most hunting or match rifles.

This video is worth the watch even if you just skip to the results, F-Class John tested runout at 1k in his comp rifle and 13 shots had .030-.045" runout (literally bent the necks) and the group ES was 9.8".

 

[SloppyJ]

It's known that expander balls in a standard FL sizing die can induce runout, however I don't think runout effects the precision as much as people believe it does. I would bet that in most cases a minor amount of runout vs perfectly concentric ammo wouldn't shoot a measurable difference in most hunting or match rifles.

This video is worth the watch even if you just skip to the results, F-Class John tested runout at 1k in his comp rifle and 13 shots had .030-.045" runout (literally bent the necks) and the group ES was 9.8".

Thank you I will check that out! I've watched quite a few of his videos along with the Winning in the Wind channel and I appreciate the info they're putting out there.

I guess my question is what induces the runout with a FL sizing die compared to a standalone mandrel? Are the mandrels built more precisely or is it something to do with the force of sizing and pulling the mandrel through in one step? Are the mandrels of different design compared between the two and if so, why doesn't someone incorporate that design into a stem that works in a sizing die?

Obviously I've never used one so there could be a big fundamental difference that I'm just not aware of. Thanks for entertaining my beginner type questions.

 

[Harvey_NW]

Thank you I will check that out! I've watched quite a few of his videos along with the Winning in the Wind channel and I appreciate the info they're putting out there.

I have too, and all I can say is take certain aspects of what they believe with a grain of salt. If you haven't already, I would definitely read the Painless Load Development thread by Form, and also listen to the Hornady podcast episodes Your Groups Are Too Small. The differences start to eclipse themselves when taken to a statistically valid sample size.

I guess my question is what induces the runout with a FL sizing die compared to a standalone mandrel? Are the mandrels built more precisely or is it something to do with the force of sizing and pulling the mandrel through in one step? Are the mandrels of different design compared between the two and if so, why doesn't someone incorporate that design into a stem that works in a sizing die?

The expander ball being incorporated with the decapping pin at the bottom of the rod, as opposed to a precision machined mandrel/die being short and at the top of the stroke. The longer the length of something, the more potential for runout. I think Short Action Customs has a modular die with an optional mandrel incorporated, but they're very expensive.

Obviously I've never used one so there could be a big fundamental difference that I'm just not aware of. Thanks for entertaining my beginner type questions.

I don't own a concentricity gauge and have never actually measured my ammo, but from what I've seen others post standard FL dies typically only induce a couple thou of runout, which I think is negligible and won't effect precision to a measurable amount. When I started down the rabbit hole my mentor told me to be cautious because you can quickly hit a point of negligible return, which I've found to be true. YMMV, I prefer KISS.

 

[Lawnboi]

I’m guessing just based off using it but;

I think that we see runout issues and pulling of the shoulder with factory dies specifically cause they squeeze the living piss out of the necks, then expand them with a large mandrel.

They are made to make everything work.

I have had no issues with expanding on the way out when using say a forester honed die or the sac die.

 

[Andouille]

I think that we see runout issues and pulling of the shoulder with factory dies specifically cause they squeeze the living piss out of the necks, then expand them with a large mandrel.

Standard FL dies and expander balls play the case necks like a brass accordion!

For example, I just measured the OD of a FL sized 300 WSM case neck at 0.326" after sizing without an expander ball. Then I expand using a mandrel and it ends up around 0.338" with a bullet loaded. 0.018" of overall movement is excessive for my personal preference, though it does shoot fine. The mandrel does seem to resize more smoothly than an expander ball, though I can't speak to any differences in the resulting accuracy.

It's my understanding that a case neck is better supported to resist the pushing force of a mandrel than pulling force of an expander ball, and the resulting concentricity is improved using an expander. That said, I like the ability to fine tune neck tension and the smooth operation of an expander ball.

 

[Harvey_NW]

I think that we see runout issues and pulling of the shoulder with factory dies specifically cause they squeeze the living piss out of the necks, then expand them with a large mandrel.

I've seen you post in the past that you've had issues, I actually pulled the ball and sized a bunch of cases and compared to with it in, no difference. Never had an issue with Hornady dies, and especially not now that I polish the ball down to .003" under bullet diameter.

There is an argument that a floating button will essentially self center and induce less runout as well, but I've never tested it. The cheapo Hornady dies seem to the job just fine for me.

 

[Lawnboi]

I've seen you post in the past that you've had issues, I actually pulled the ball and sized a bunch of cases and compared to with it in, no difference. Never had an issue with Hornady dies, and especially not now that I polish the ball down to .003" under bullet diameter.

There is an argument that a floating button will essentially self center and induce less runout as well, but I've never tested it. The cheapo Hornady dies seem to the job just fine for me.

I think a lot of it has to do with brass choice and how the die works with it. Also that I anneal every firing, which leaves me with next to no spring back.

I can’t speak to Hornady but I specifically had issues with redding. Just too much sizing being done.

Conversely I do mandrel on the out stroke, say like a button would currently with sac dies. I’m just only moving the brass a couple thou. My brass is more consistent than it ever was, including using a mandrel as a separate step.

 

[TaperPin]

Has anyone used a holder that allows standard machinist gauge pins to be used as the mandrel?

The pins are quite a bit less expensive - a set of 10 carbide pins in .0004” increments is only about $100, or a full set of pins to cover all cartridges in .001” increments is about $200.

 

[wapitibob]

Has anyone used a holder that allows standard machinist gauge pins to be used as the mandrel?

The pins are quite a bit less expensive - a set of 10 carbide pins in .0004” increments is only about $100, or a full set of pins to cover all cartridges in .001” increments is about $200.

I looked into it a bit and think I remember somebody selling a collet type holder. I stopped looking when I stopped expanding the necks.

 

[SloppyJ]

Standard FL dies and expander balls play the case necks like a brass accordion!

For example, I just measured the OD of a FL sized 300 WSM case neck at 0.326" after sizing without an expander ball. Then I expand using a mandrel and it ends up around 0.338" with a bullet loaded. 0.018" of overall movement is excessive for my personal preference, though it does shoot fine. The mandrel does seem to resize more smoothly than an expander ball, though I can't speak to any differences in the resulting accuracy.

It's my understanding that a case neck is better supported to resist the pushing force of a mandrel than pulling force of an expander ball, and the resulting concentricity is improved using an expander. That said, I like the ability to fine tune neck tension and the smooth operation of an expander ball.

What would an ideal amount of differential be for you based on neck OD? I've noticed what I consider a very small amount of work being done on the 100 300prc cases I sized last week with my Forster FL die. My first time using Forster stuff but I really like them.... almost as much as the RCBS competition seating die I got for it too.

 

[TxLite]

I just use whatever the FL size die comes with. Accuracy/repeatability hasn’t been an issue for me. Maybe ignorance is bliss?

 

[DangerRanger]

I do not expand, bushing dies to size and move on

 

[Harvey_NW]

Has anyone used a holder that allows standard machinist gauge pins to be used as the mandrel?

The pins are quite a bit less expensive - a set of 10 carbide pins in .0004” increments is only about $100, or a full set of pins to cover all cartridges in .001” increments is about $200.

I looked into this too, I think Lee makes a collet die, but I also think the RCBS collet bullet puller would work to lock a gauge pin in. May have to modify a collet to cinch down tight enough, and no telling if it would be as perfectly concentric as a die/mandrel setup, but I think it could work.

 

[Andouille]

What would an ideal amount of differential be for you based on neck OD? I've noticed what I consider a very small amount of work being done on the 100 300prc cases I sized last week with my Forster FL die. My first time using Forster stuff but I really like them.... almost as much as the RCBS competition seating die I got for it too.

"Ideal" depends on you! @TxLite has a valid point that ignorance can be bliss if the result works. I like to tinker and optimize, so I'm looking for less than 0.005" of neck diameter change during the resizing process with bushings and maybe "light" touch with mandrel if necks aren't round.

 

[Mike D Texas]

Thank you I will check that out! I've watched quite a few of his videos along with the Winning in the Wind channel and I appreciate the info they're putting out there.

I guess my question is what induces the runout with a FL sizing die compared to a standalone mandrel? Are the mandrels built more precisely or is it something to do with the force of sizing and pulling the mandrel through in one step? Are the mandrels of different design compared between the two and if so, why doesn't someone incorporate that design into a stem that works in a sizing die?

Obviously I've never used one so there could be a big fundamental difference that I'm just not aware of. Thanks for entertaining my beginner type questions.

Mandrels allow you complete control over the amount of neck interference. Most expander balls are of a generic size yet brass thickness varies by manufacturer.

Also addition stress is induced on the neck and shoulder with an expander button vs mandrel, specifically when pulling back through after sizing the neck.


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