Expander flaring question

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  • Last Post 02 February 2024
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max503 posted this 31 January 2024

 This is about reloading lead and powder coated rounds for my Rossi 357 rifle.  I use an old set of RCBS steel dies.  The expander ball measures .3555".  Not having pin gauges, the nearest I can tell, that die produces cases with an I.D. of .355".  

Normally, for lead loads out of a 357, you would size to .358".  Well, my Rossi shoots best with boolits sized to .3565".  That's what my tightest sizer die produces.  

I'd like to experiment with cases with a larger I.D.  My questions are: Can I purchase a larger expander for this die?  My other question is, if I got on a lathe and made an expander, what size threaded rod/bolt would I make it out of?  The threads on the expander measure .558".  I couldn't match that up to an existing thread size.  

Hope that makes sense.  Here's a pic of the expander:

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MarkinEllensburg posted this 31 January 2024

What you are asking is will a .0015" difference between your case inside and the bullet outside be too much tension thus sizing the bullet smaller? I don't have the answer to that. There's lots I have just not measured and geeked out on to use a in vogue term.

As far as buying a lathe and turning one sized to your dimensions, the thread has a diameter and a pitch in turns per inch. Match the diameter of the threads and set your lathe by whatever means it has to obtain the correct pitch. It is not something that is just that easy though. Buying a lathe is a rabbit hole and could lead to obsessive behavior. First you buy a lathe, then you buy tooling, then you buy stock, do a few projects, then you buy more stock and more tooling and soon you will want a mill or a way to mill on the lathe. Then you want measuring tools and a surface plate and more tooling and more stock. Soon you will have spent far more to solve things than what paying someone else to do it for you would have cost but the ride is good and you might be happy...

 

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Wilderness posted this 01 February 2024

Max - Lyman M Die stems, available as a part, are the same thread as the RCBS expander. But then of course you need to know the Lyman plug diameter.

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Boschloper posted this 01 February 2024

I have made several expanders for Lee “powder thru the expander” dies. It’s not hard if you have access to a lathe, but you will need to heat treat your expander after you make it or it won’t last long. 

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wimilkman posted this 01 February 2024

You might want to take a look at Noe expanders it’s the same company that makes bullet molds . I have them for 9mm , they come in different sizes and work quite well it would save you a lot of time and money versus trying to make your own. I have there powder thru ones as I have all Lee reloading equipment and drop my charges on the press , I use a .357 Noe expander for a .355 bullet, a .358 for a .356 bullet they have them for most calibers hope this helps. Fred

Fred Honeyager

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Glenn R. Latham posted this 01 February 2024

Max, the threads are 9/16-18.  9/16 comes to .5625", but the crest of the threads is reduced a bit for clearance.  The NOE plugs are a good deal.

Glenn

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mashburn posted this 01 February 2024

If you have an oddball expander plug, that is larger, and one for which you have no use, just turn or sand it down and screw it on. If no lathe is available, you can chuck it up in a hand drill chuck and back a piece of sand paper with something like a file, and turn the drill on and hold the expander plug against the backed sandpaper. It might help to practice on a round piece of steel before you sand the expander plug. Ii never get rid of old dies so that I have parts without having to wait on an order.

Mashburn

David a. Cogburn

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Aaron posted this 01 February 2024

The RCBS Cowboy die set will solve the matter for you. The expander is slightly larger to accommodate lead pills without squeezing the poo out of them, yet maintaining good neck tension.

 

With rifle in hand, I confidently go forth into the darkness.

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max503 posted this 01 February 2024

Ahhh.  On further research, I think my problem is solved.  I came across this thread on the Castboolits site.  It explains my confusion perfectly.

https://castboolits.gunloads.com/showthread.php?303063-Can-someone-explain-NOE-expander-plugs-and-dimensions

After reading that thread I went to the NOE site and found what I was looking for.  I ordered the .362 x .358.  (I figure if it is too loose I can easily sand off a thousandths or two from the sizing stem).  Those go into the Lee Universal Expander Die.  I know I've done this before.  But its been a while and I was having one of those senior moments.  

But now I'm good.  Thanks all.  Your posts pointed me in the right direction and I am indebted to you all.  Happy shooting!

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alphabrass posted this 01 February 2024

I'll second Mark's remarks about the lathe.  I've done all that, exactly as he laid it out.  I make expanders for Lyman M dies, very simple to do.  12L14 steel works fine and is easy to machine on a small lightweight lathe.

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MP1886 posted this 01 February 2024

I have a lathe and I've made a lot of reloading items that are hardened from the factory, that have not worn out easily. Maybe the difference is I make my items from hardened steels in the beginning. 

It is my opinion that the best flare for loading cast bullets, even jacketed, is the bell flare. Many of you don't know it but the Lyman M die still leaves a rather steep ledge in the transition form the wider expansion starting at the mouth to where the step is and with the softer cast bullets this does size the bullet down some. The M die also leaves the case mouth in a state that isn't friendly with roll crimping. It's okay for taper crimping. In my experience the case should be expanded no more then .0015 then the diameter of the casta bullet to be seated. 

With this said I feel the RCBS expanders, the ones that sold separate with different sized expander tips, and the LEE tapered expander which is also a separate tool to be the best to use. I won't talk about NOE because I've never used them.  I'm not mocking NOE, but he does make products that are copies of other companies out three and that is all well and fine because he provides us with need tools when the others aren't available. Same with his bullet moulds. I'm glad he makes copies there. 

After you've made an expander on your lathe and you've gone through the various stages of polishing it, you should finish the polish with red jeweler rouge.  Make sure you compensate for the diameter change in your polishing methods. 

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Larry Gibson posted this 01 February 2024

NOE makes excellent moulds and other tools.  They make moulds which are what their customers want.  Unless there is a patent or copyright infringement there is nothing wrong with it.  The similarities of many cast bullet designs made by most mould makers is the same. 

MP1886, you had a good post going until you started trashing someone, again.  Do yourself and us a favor and delete that part of your unwarranted comments as it does not relate to the thread.

LMG  

Concealment is not cover.........

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MP1886 posted this 01 February 2024

NOE makes excellent moulds and other tools.  They make moulds which are what their customers want.  Unless there is a patent or copyright infringement there is nothing wrong with it.  The similarities of many cast bullet designs made by most mould makers is the same. 

MP1886, you had a good post going until you started trashing someone, again.  Do yourself and us a favor and delete that part of your unwarranted comments as it does not relate to the thread.

LMG  

 

 

You must have a reading comprehension problem or you're reading WHAT you want to see. If you reread it I basically said what you were saying. I even stated that I bought NOE moulds. The part about patents and such stem which you do not know about is that a friend who had a falling out with 45.2.1 and had a falling out had all of his bullet designs and gave them to NOE to spite 45 2.1.  45 2.1 did contact NOE about this. The only reason NOE came up in that post is I was explaining I couldn't comment on his neck expanders as I don't use his, which is what the threat is about. 

I also don't need any pats on the back from the likes of you. With that said I can't believe you off all people agreed with the expander part. I'm going to add to it. Lyman has a separate M type expander for cast bullets. They are getting closer to doing it right. Lyman increased the diameter of the part of the neck that actually grips the cast bullet knowing that jacketed bullet neck tension is not good for cast bullets. They also made it so you could turn the die down some so as to put a bell or flare on the case mouth. DUH DUH, it's that one of the things about expanding not only cast bullets, pc bullet, paper patched bullets, and thin copper plated bullets????The assinine thing about the M die is you don't need that first expansion starting at the case  mouth.  Like I said it interferes with roll crimping and it also lessens the amount of the case neck that holds tension on the bullet whether jacketed or cast. Now if they want to improver their cast bullet M die they need to tapered the ledge or seat (whichever you wish to call it) instead of having the shoulder they use which sizes down cast bullets especially softer alloys. Nobody else uses this M die setup. RCBS expander system is far superior. 

Last, but not least, you have no authority or right to be telling members what to do or not do on their post. 

 

Oh I'm editing to add  Have a good day Larry.

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Larry Gibson posted this 02 February 2024

max503's questions [and the topic of the thread]  are;

"My questions are: Can I purchase a larger expander for this die?  My other question is, if I got on a lathe and made an expander, what size threaded rod/bolt would I make it out of?  The threads on the expander measure .558".  I couldn't match that up to an existing thread size."  

Whether or not one can purchase a larger expander for the RCBS die body can only be answered by RCBS.  

The rod size should be 1/4 x 28 as it is on my RCBS expander die.  That is the standard size rod used in many RCBS dies.  It is uses for the decap rod and seater stem.  A long replacement can be got and adapted to duplicate the one in your die.  However, the expander should screw off the rod(?) so the same rod can be used.  

That .588" measurement, is it the depth of the threaded hole or the diameter of the rod?

LMG

Concealment is not cover.........

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MarkinEllensburg posted this 02 February 2024

.558 is the thread diameter of his expander. 9/16x18 thread. All RCBS pistol die sets that I own are this same size.

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MP1886 posted this 02 February 2024

max503's questions [and the topic of the thread]  are;

"My questions are: Can I purchase a larger expander for this die?  My other question is, if I got on a lathe and made an expander, what size threaded rod/bolt would I make it out of?  The threads on the expander measure .558".  I couldn't match that up to an existing thread size."  

Whether or not one can purchase a larger expander for the RCBS die body can only be answered by RCBS.  

The rod size should be 1/4 x 28 as it is on my RCBS expander die.  That is the standard size rod used in many RCBS dies.  It is uses for the decap rod and seater stem.  A long replacement can be got and adapted to duplicate the one in your die.  However, the expander should screw off the rod(?) so the same rod can be used.  

That .588" measurement, is it the depth of the threaded hole or the diameter of the rod?

LMG

 

Well me to the rescue again. You don't have to call RCBS.  I can answer for you. Yes you can buy just the expander balls.  Look here:

https://www.midwayusa.com/product/1012109861?pid=783273

 

Have a good day Larry.

 

 

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Wilderness posted this 02 February 2024

I might be the odd one out here, but I actually prefer the design of my Lyman M Dies over the RCBS (which I also have).

I neither trim nor crimp my .30-30 cases. My chambers are way too long for even a maximally stretched .30-30 case, so I just let them grow until something kills them - and it won't be mouth splits. Ditto my .32-40 cases made from .30-30s and ending up short.

The M Die will be set to provide just enough second stage expansion for the shortest case. The depth of this larger diameter expanded portion will vary, but the portion that applies the grip to the bullet will be the same length on all cases.

By contrast, the RCBS (and Lee) dies if applied to cases of slightly differing length will apply everything from just enough flare up to a trumpet lookalike, and the length of grip will be variable.

With this setup I can avoid a general trimming of my cases just to bring them into line with a few shorter ones.

This preference of course applies just to those situations where variable case length is not a sin, or perhaps it is how we stop variable case length being a sin.

Sorry - a bit off topic.

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max503 posted this 02 February 2024

max503's questions [and the topic of the thread]  are;

"My questions are: Can I purchase a larger expander for this die?  My other question is, if I got on a lathe and made an expander, what size threaded rod/bolt would I make it out of?  The threads on the expander measure .558".  I couldn't match that up to an existing thread size."  

Whether or not one can purchase a larger expander for the RCBS die body can only be answered by RCBS.  

The rod size should be 1/4 x 28 as it is on my RCBS expander die.  That is the standard size rod used in many RCBS dies.  It is uses for the decap rod and seater stem.  A long replacement can be got and adapted to duplicate the one in your die.  However, the expander should screw off the rod(?) so the same rod can be used.  

That .588" measurement, is it the depth of the threaded hole or the diameter of the rod?

LMG

 

Well me to the rescue again. You don't have to call RCBS.  I can answer for you. Yes you can buy just the expander balls.  Look here:

https://www.midwayusa.com/product/1012109861?pid=783273

 

Have a good day Larry.

 

 ________________________________________________________________________________

Thank you for letting us know about this other good option.  Since I already own a Lee expander, and NOE makes plugs to fit it, I will just stay with what I've got.  But yes, according to your post RCBS sells a .358" expander that would fit my needs.  

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Larry Gibson posted this 02 February 2024

 Max503

The expander plug MP 1886 has referred you to is the one, like mine, that fits on a 1/4x28 rod.  What you have is a pistol expander die in which the expander part is an integral part of the expander plug.  Again, I suggest a call to RCBS to see if the make a .358 one.  The Midway part MP 1886 suggest is the wrong part.

I'll check my own RCBS 38/357 dies and see if I can get a measurement on the thread size.

Thread size is .556 to .358 x 18 on 4 of my RCBS pistol expanders.

You might consider getting the RCBS universal expander die with the .358 plug MP 1886 suggested?

And, for MP 1886s edification I am having a great day......

LMG

Concealment is not cover.........

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MP1886 posted this 02 February 2024

larry the expander I'm talking about here is as you said the Universal Neck Expander.  Over the decades RCBS, like other's have changed things. For example rememeber when their bullet seating die was solid with a small hole at the top for the bullet seating stem to pass through? It was also a smal diameter threaded stem, not the 1/4x28 most use today. They did this on some other dies too.  The one that peeves me the most is Hornady pistol dies, unless they changed it again, and that is the pistol expander die. The expander stem is pressed in, nothing you can do with it. So they thought. I just put it in my lathe and center drill a small hole through the top and then taks a punch and punch the expander out after I threaed the die in my press. Then you can do as you please with it except you can't make it larger unless you make one on the lathe. Nope don't like their arrangement at all. 

I'm glad you are having a good day, keep it up. 

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Larry Gibson posted this 02 February 2024

Nice walk back......

Concealment is not cover.........

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