Another mandrel post.....help

[Wildstreak]

When I started handloading I probably like most, I used a 2 die set that included a full length sizing die with an expander ball and a seating die. When I learned about neck bushing dies I made the switch pretty quickly, they made sense to me. I currently use Redding S-type 3 dies sets with a bushing neck sizer and separate body size die. Now it looks like a lot of folks are making the move to expander mandrels. As far as I can tell a mandrel and button do close to the same thing with the exception that a mandrel gives you size options to customize how much you want to open the neck and they size the neck on the downstroke as opposed to pulling up on the brass on the upstroke. But what I don't understand and maybe I am just an idiot (which is often the case) is I have seen/heard/read folks using both the mandrel and a bushing.

Why is this better? How do I determine what size mandrel to use?

 

[dok7mm]

I don't use the bushing dies any more. I use a FL die minus the button. Or a body die + a generic neck die to reduce the neck size.

Then I use my mandrel usually .002" under bullet diameter, .262" for 6.5, .282 for 7mm, etc.

In the past few years, we can use mandrels sized to 4 decimals instead of 3. So for a 6.5, I can use .261", .2615", .262, .2625" to see what "tension" works best.

Spring back using mandrels pushes inside, where as bushing is the opposite.
A mandrel also gives a more concentric neck I.D. than a bushing for non-turned necks. With turned necks, bushings seem to do well for those who go that way.

 

[Longtine88]

When I started handloading I probably like most, I used a 2 die set that included a full length sizing die with an expander ball and a seating die. When I learned about neck bushing dies I made the switch pretty quickly, they made sense to me. I currently use Redding S-type 3 dies sets with a bushing neck sizer and separate body size die. Now it looks like a lot of folks are making the move to expander mandrels. As far as I can tell a mandrel and button do close to the same thing with the exception that a mandrel gives you size options to customize how much you want to open the neck and they size the neck on the downstroke as opposed to pulling up on the brass on the upstroke. But what I don't understand and maybe I am just an idiot (which is often the case) is I have seen/heard/read folks using both the mandrel and a bushing.

Why is this better? How do I determine what size mandrel to use?

You still have to size your neck down even for the mandrel. With a bushing or FL die I bump my shoulder back the 0.002. Depending on how much you size the neck you're going to have to play with the mandrel size until you get the tension you want. So if I were trying to get a neck tension of .002 for say a 30 cal I would pick the 0.3070" mandrel because your neck generally will fall back depending on how much I squeezed the neck die. If I use a bushing die and the bushing gets me to my 0.002" perfect then I still will run my 0.3075" mandrel through it and then it's perfect. People will say you're just wearing out your neck, but since I anneal after every firing it really doesn't matter. The combo works for me. I produce a lot of one hole groups so I guess the proof is in the pudding.

 

[Longtine88]

And like David said, I do have two barrels that I use a body die on, then size the neck and run a 0.3070" mandrel through. Remember the more you squeeze your neck down, the more it will bounce back after the mandrel is run through it.

 

[PddPdd]

OP, I believe people use both bushing FL sizing dies with mandrels because you can reduce working the brass by controlling exactly how much you squeeze the neck O.D. down during FL sizing and exactly how much you open it up with a mandrel to a half of ten thousandth of an inch (.0005").

A secondary benefit of having a set of mandrels is you can accurately assess neck I.D. for any process you are using.

 

[Mikecr]

Originally, mandrel use was an alternate to standard buttons provided.
Mandrels contributed less to loaded runout than buttons,, they didn't offset necks or roll brass up into donuts.
And expander mandrels (from turning systems) were more reasonable/appropriate in upsizing dimension.

Neck expansion is a pre-seating operation that biases neck spring back inward, instead of outward.
I'm sure it was well learned ~100yrs ago that neck tension would decrease over time -without expansion as a last sizing step.
Why else would would it be so consistent that any neck sizing in dies includes pre-seating expansion?
Didn't happen by chance, and I doubt there is improvement with removing of expansion. You'd just be using bullets for expanders instead of hardened mandrels.

I was actually the person who brought this to forums, and tried to convince potential in it ~30yrs ago.
It's just recently taken hold, and quickly turned into an absurd monster.
Pretty much as everything does today...

 

[Wildstreak]

Looking at the 21st century mandrels. Any reason to get the black nitride over stainless? Should I consider another brand?

 

[PddPdd]

I purchased about 30 mandrels from Porter Tooling in Texas if I remember correctly. They were priced right and have worked well. You should be able to find their information on this site with a search on "mandrels".

 

[QuietTexan]

Looking at the 21st century mandrels. Any reason to get the black nitride over stainless? Should I consider another brand?

The steel ones have worked fine for me. If you want the nitride get it, but I lube necks when using mandrels and take it off with a rice tumble after.

I've mic'd every 21st Century mandrel I've bought, and a grand total of one wasn't to spec at the correct 0.0005" exactly. It was off by a full 0.0010" so probably got mishandled and ended up with the wrong laser mark. They sent me a correct one no questions asked.

Two reasons I went with 21st Century over Porter Precision: PP uses Class ZZ pins with themselves are only specified to 0.002" tolerance, and they use a collet system. I prefer the 21st Century/ Sinclairs/ PMA system with the stepped top and more positive lock in the die, and the turned mandrels aren't a solid length all the way down but have a bulge on the end so there is positive feedback on clearing the neck.

You don't have to buy pins directly from Porter to use with their system, you could order ZZ- or X-Pins from Grainger and taper them yourself. They're charging about $4 per pin to taper the end.

 

[crashlanding]

So what would be the down side to just using a Lee neck collet die? I'm learning here and want to be schooled

 

[QuietTexan]

So what would be the down side to just using a Lee neck collet die? I'm learning here and want to be schooled

Absolutely nothing is wrong with Lee collet dies, I have a bunch and use them often in the early loading phase of letting the case reach it's maximum chamber demensions. I think Lee is back to offering custom undersize mandrels again, they can give you basically the same options to the 0.0010" as mandrel sets do. Limited offerings of chamberings available, but again their custom shop will make pretty much anything you ask for.

The one thing they won't do is any body sizing so you either have to pair them with a body die to use long term, or switch over to some kind of a FL/bushing die at some point.

 

[DoneNOut]

I pulled the decappers/buttons out of my FL dies
I use an RCBS universal decapper
I anneal the cases prior to sizing and mandrel use
I use 21st Cent mandrels (Stainless with some imperial sizing wax)
I noticed increasing the ID of the brass by at least .003" with a mandrel allows the brass to stay at that setting.
Hammer bullets get .004" interference fit and Bergers .0015". Incredible results on target!

Funny the Lee collet die was brought up. I loaded with Lee dies many years ago, and before I had any clue about "neck tension", I would reduce the rod to get more neck tension. Well, Lee supported the .0015-.002" neck tension and I was a heathen. Now I understand what Lee was doing. LOL.

 

[Mikecr]

I would never FL size necks, LCD or otherwise.
Prefer partial length sizing

 

[DoneNOut]

I would never FL size necks, LCD or otherwise.
Prefer partial length sizing

Why is that? Even semi-autos?