Case Mouth Expander Dies

[Mixed Nuts]

I have an RCBS die set for .357 magnum. The case mouth expander die is the stepped type. As the ram is lifted, the expander plug enters the case mouth and goes in quite a way before the case mouth reaches a slight step on the expander plug that slightly increases the mouth and makes a starting point for cast, flat base type bullets.

This RCBS die nearly always leaves a slight, offset bulge in the expanded brass.

I've tried the die in two presses and I've taken it apart but I can't find anything wrong or anything inside to adjust. Also, other dies in the set seem to work fine.

I think the expander plug (could be called plug - not sure of name) must be threading into a die body that was tapped slightly canted.

Is there some other explanation? Could I be making a mistake expanding that I don't realize?

 

[ArchAngelCD]

You should call RCBS and ask them. They are of course the one to answer questions about their dies. They just might have you send it back for repairs/replaceme.

 

[Mixed Nuts]

You should call RCBS and ask them. They are of course the one to answer questions about their dies. They just might have you send it back for repairs/replaceme.

I may have to do that. Was hoping someone might have had my same experience but found a solution in use or adjustment of the die.

 

[9mmepiphany]

This RCBS die nearly always leaves a slight, offset bulge in the expanded brass.

Can we see a picture of the "offset"?

Can we assume that by "offset", you mean it only budges out on one side...so that the case mouth is no longer round

 

[Mowgli Terry]

Right, a picture would help all unravel your problem. I'm confused how a mouth expander could end up with your having to pull bullets. I have used the Lee Universal neck expander with success. Don't know if the Lee would help. I have not used RCBS handgun dies in many years. .

 

[Walkalong]

Is there some other explanation?

Bad seater. Starting bullets crooked.

 

[Varminterror]

Bad seater. Starting bullets crooked.

Too much (sometimes too little) flare and ^this.

 

[Walkalong]

I think the expander plug (could be called plug - not sure of name) must be threading into a die body that was tapped slightly canted

Is RCBS making them two piece like Lyman now? If so, could be.

 

[Laphroaig]

When I read the OP I get that the bulge in the case occurs while expanding before a bullet is seated.

Could it be that the plug is not centered in the die? I'd try raising the ram into a case with the lock ring loose so that the plug will be centered by the case. Tighten the lock ring at the top of the stroke and see if the results are better.

Edit: what I meant to say was tighten the locking nut that secures the plug to the die.

 

[beag_nut]

I use the Lyman expander die. Absolutely no problems, ever.

 

[Mowgli Terry]

Not enough information: I still think we need a photo. It hard to wrapped around this idea. How could a case still be goofed up that it would not be usable after a trip through most bullet seaters. Sounds like there is a communications problem. On this end I'm trying to be of assistance without really knowing the problem. What was happening to make bad loads after the case was crimped. Wonder if the problem came from the "shadow" of the bullet being on the outside of the case. That's not a problem.

 

[9mmepiphany]

Bad seater. Starting bullets crooked.

That was my first thought also, but a couple of things posted added doubt.

slight, offset bulge

I wondered if there was confusion between bulge and the seating cup formed

kinetic bullet puller

If the bulge occurred during expansion, why/how would/could he have loaded them

 

[mdi]

If the plug is threaded into or on the die body, perhaps you could leave it loose and allow it to "float", center itself...

 

[larry7293]

RCBS expander pistol dies are the step type. I have had good luck using them in 357mag and 44mag. Much better than the Lee expander die.

 

[9mmepiphany]

RCBS did themselves a solid when they copied the Lyman M die

 

[Mixed Nuts]

MPI and Laphroaig, these are interesting suggestions. Tomorrow, I’ll get the press down, set up and test this out.

The problem is with the empty sized cases. The bulge is low, a third of the way down the case and on “one side.” Side is a funny word for describing a flaw on a cylinder but I think you’ll get my meaning. The RCBS expander die goes deep into a case, imitating a bullet, before the case mouth reaches the step that precedes the flare on the RCBS die plugs - the stepped type made after 2010. It is as if the insertion is slightly canted, and that the cant is personified as the expander plug travels further into the case.

I spent last night running the cases through the sizing die – each one multiple times – to work out the bulge in each case. I don’t have a bad case handy but could put one together tomorrow.

 

[Mixed Nuts]

I use the Lyman expander die. Absolutely no problems, ever.

I ordered this very die. But today, was out and bought a Hornady set. After a cursory look, I'd say the RCBS has a better expander design. That is, if it would work.

 

[Mixed Nuts]

Yes, good point

 

[Mowgli Terry]

We need a picture since what you are saying is confusing. You expander die does not have anything to do with concentric cartridges. Why do you need to pull the bullets? I'd suggest you look to your bullet seater. You may consider getting a case gauge to check your cartridges. Do these cartridges chamber? Have you used your barrel for a case gauge? What I am trying to say is that if you are asking help us folks out here need more information. Bulge and non-concentric do not have a meaning. Pictures would help. That, or get you another set of dies.

 

[Mowgli Terry]

Sorry, we are out of sequence. This third of the way down the case is the max. My mistake on not being mindful of your handgun being a revolver. All this makes less sense with each post. Sorry not an expander problem. This is getting to be from Cloud Cuckoo Land. There's enough of that now in everyday life.

 

[WestKentucky]

Just exactly what bullet are you using? I have known good dies that have caused me fits with some bullets where the bases are super duper flat. I realize that almost all .357 bullets are “flat base” but most are in actuality rounded which helps them slip into the cases. Really flat bases with sharp corners are no bueno.

 

[Mixed Nuts]

yes, good point

 

[Mixed Nuts]

Sorry, we are out of sequence. This third of the way down the case is the max. My mistake on not being mindful of your handgun being a revolver. All this makes less sense with each post. Sorry not an expander problem. This is getting to be from Cloud Cuckoo Land. There's enough of that now in everyday life.

I wasn't able to understand this.

 

[Mowgli Terry]

Sorry, this is outside my forty plus years of handloading. I'd suggest you call RCBS and/or send your dies back. To me, this case damage, as you explained it, is impossible. Produce pictures to prove me wrong.

 

[Mixed Nuts]

Sorry, this is outside my forty plus years of handloading. I'd suggest you call RCBS and/or send your dies back. To me, this case damage, as you explained it, is impossible. Produce pictures to prove me wrong.

Okay, Mowgli. Thanks. I'll try to get a picture today after setup.

Do you use RCBS expander dies for .357 made after 2010? If you don't, perhaps this is the pont where our discussion becomes confused.

Also, I have no desire to "prove you wrong." Just pulsing the community here to see if I missed something or if this expander problem has been seen before.

Some expanders for .357 just open the case mouth a touch. My new Hornady expander and my Lee classic loader expander are that type. But the RCBS expander, by design, goes far into the case. I think the idea is to create a concentric channel before seating to keep the seating more precise. Trouble is, my die isn't doing that. It's inserting off-center.