Case mouth expanding and flaring

[Mixed Nuts]

I prepped some .357 magnum brass yesterday using two of the three dies in an RCBS carbide die set for .38/.357/.357 max.

Sizing and decapping went very well. And on the whole, expanding the case mouths and flaring them slightly for 158 grain cast LSWCs went okay.

However...

The RCBS case mouth expanding die is the stepped type. At the top of the case mouth expanding portion of the expander there is a slight "step" that additionally expands the mouth before the tool widens dramatically for flaring.

The previous paragraph may not be relevant to my questions...

Question one: the instructions tell me to screw the expander (within the die) down into a case until I feel it hit the "step." (There are more instrutions, too. Just not mentioned here) This is quite challenging to do, as the expander gets harder and harder to screw as more and more brass grabs the side of the tool as it goes deeper. Is this normal? Is it really supposes a finger power strength test to set up the expander die?

Question two: two of the cases bulged noticeably from the expansion. What I mean is - they expanded in a non-concentric sort of way... as if the case bent in the shell holder and the expander tool entered the case mouth crookedly.

I could not resize the bulges out entirely and I chucked the brass.

I got to thinking that if I could see a couple obvious fails, that more subtle mistakes might be all through my brass.

Anyway, question two (and maybe three): how do I improve or ensure concentric case mouth expanding for .357 magnum cases? And is my case mouth expansion issue a common problem?

 

[dgod]

The way I do my Case Expansion is to gradually set the Expander, try a piece of Brass, not enough, turn 1/2 turn, try again, same piece of Brass, repeat until desired results. Lock it down.

As for the bulge, prolly due to Brass not all the way seated/crooked in the shell holder.

Good Luck,

Dan

 

[higgite]

I think you are doing it the hard way. At least, the hard on the fingers way. This is how I set up my RCBS expander die for 9mm. Should work the same for your .38/.357.
1. raise the ram to the top of its stroke and hold it
2. back the expander plug almost out of the die
3. screw the die into the press until it hits the shellholder and lock it down
4. lower the ram and insert a case in the shellholder
5. raise the ram to the top of its stroke again and hold it
6. screw the expander down until it hits the case mouth plus a little bit
7. lower the ram and try setting a bullet in the case mouth
8. if the case mouth isn’t expanded enough, screw the expander stem a little farther into the die and repeat steps 7 and 8 until you get the right amount of expansion

 

[wrench459]

When all said and done the boolit should rest in the mouth fairly straight up right.

 

[Walkalong]

This is quite challenging to do, as the expander gets harder and harder to screw as more and more brass grabs the side of the tool as it goes deeper. Is this normal? Is it really supposes a finger power strength test to set up the expander die?

Sounds like you are trying to screw it down into a case. Raise it, adjust it down a hair, try it again. Always adjust it out of the case.

I think you are doing it the hard way.

Yep.

 

[Mixed Nuts]

Dgod, yeah, that must be the way. Just needed to get all the way down the first part of the expander, over the step and then a hair up the flare for the cast bullets. Wasn't sure what that should look like so I tried the instructions to a T. Your way is my new way.

Thanks higgite, appreciate the step by step.

Wrench459, they did, at last, and they went in nice, maybe a tiny bit of shaved lead on a few, but it was like spider web thick.

Walkalong, thanks. I'm gonna adjust with the case out from now on.

Loaded 4 loads in .357 mag with accurate no9. under a 158 lswc. 12.4 gr, 12.8gr, 13.2gr and 13.4gr.

Hope I find a good load in that bunch.

 

[243winxb]

Looks like 12.4 gr is maximum? http://www.accuratepowder.com/load-data/

 

[Mixed Nuts]

Maximum? I hope not.

I'm looking in the lyman load data mini book entitled Popular Revolver Calibers. Page 48, the loads for the lyman #358665 158grain cast bullet. Is not LSWC, but same weight and also cast.

The start load is 12.4, giving 1147fps at 30900 CUP.

The max load is 13.7, giving 1327fps at 42200 CUP.

Thanks for making me recheck 243winxb. Is never bad to recheck.

 

[243winxb]

http://stevespages.com/page8a.htm

AA-9 From 9.7 grains to 16.0 grains

From Accurare powder-

As long as the numeric/s is/are the same, i.e. examples, “A” or “AA” no9” or “A” or ‘AA” 4350” the burn rate and load data will be the same. The “XMR”and “XMP” prefixes, and/or “BR” post-fixes was eliminated ca 2003 and does not apply anymore.

Also since the Accurate Arms Company does not exist anymore (Since late2004/early 2005 when they sold out to Western powders Inc) the “AA”prefix is also not applicable anymore.

The powders are merely designated with an “A” prefix or the full name “Accurate”.

The “Scot” name used on some of the shotgun powders i.e. Scot Solo1000 is also not been used since 2003.

Starting low and working up, only way to know.

 

[Mixed Nuts]

Interesting, 243winxb. I called Accurate today at 406 234 0422, and asked a guy named Rob if the AA no.9 and the Accurate No. 9 were the same thing and he said yes.

The load I'm referencing lists the powder as Acc. #9. But I called Accurate because I was looking at several other loads, one in particular in the loose bound "The Complete Reloading Manual for the .357 Magnum."

That load listed a 168grain lyman #358429, (which is a LSWC) starting at 10 grains of AA 9 and running up to 13.5. I figured if one could load 13.5 under a 168grain LSWC then I'd be safe loading 13.4 under a 158.

I'm a little nervous now. I thought I was playing it safe. Now, you've got me wondering.

 

[Riomouse911]

Higgite has it right, a little bit of adjustment at a time makes life easier. Hopefully that post solves your issues

 

[9mmepiphany]

The RCBS case mouth expanding die is the stepped type. At the top of the case mouth expanding portion of the expander there is a slight "step" that additionally expands the mouth before the tool widens dramatically for flaring.

If you are running the case up enough on the expander to get to the above bolded section, you're running it in too far.

Like the original Lyman M die, the RCBS Expander forms a "seat/cup" with that "step". That seat, with it's parallel sides, holds the bullet vertically in the case mouth as it is inserted into the Seating die.

If you are running the case pass this "step", you're defeating the purpose of the die's design

 

[Mixed Nuts]

Riomouse911, thanks. I concur.

9mmepiphany, maybe for jacketed ammo. But a slight flare is not discouraged for cast bullets in the RCBS directions for .357 mag when using the stepped die. Perhaps for the 9mm, or other auto calibers, with their taper crimp, RCBS includes a different manual? I dunno.... the step in the case is not erased by a flare, the step remains, or it seemed to. Perhaps if I flared more aggressively it would dissapear.

Mmm.. as I think about this is see your point. Yet, if I didn't flare I'd shave lead all over.

 

[Walkalong]

9mmepiphemy is correct, you often times don't have to use the flare part of the "M-Die" design, regardless of the die maker (RCBS & Redding both copy the design now), unless it doesn't open it enough without it. That second step, or "seat/cup" as described above, is often enough, but if it isn't, yes, a slight flare will be needed on top of that. For plated and jacketed it shouldn't be needed, but some lead and coated may need it if they are too fat. And of course the die could be slightly out of spec, but I agree with RCBS, sometimes a tiny bit of flare can be needed besides just the second step, which should (The 2nd step) leave the case mouth ever so slightly above bullet diameter.

 

[dgod]

Walkalong, Amen

 

[Mixed Nuts]

Walkalong, I see his point, any but the most gentle flaring will flare out the step made in the case mouth. Totally makes sense. Yet, even with my modest flaring I got a few wispy shavings of lead now and again. I appreciate your response as sometimes it takes two in agreement to sell a POV.

Dgod,... Or three in agreement.

 

[9mmepiphany]

Yet, even with my modest flaring I got a few wispy shavings of lead now and again.

I believe that has quite a bit to do with varying case lengths...unless you already sort, trim, bevel, and chamfer the cases

 

[Walkalong]

I believe that has quite a bit to do with varying case lengths...unless you already sort, trim, bevel, and chamfer the cases

A very real possibility.

 

[Mixed Nuts]

9mmepiphany, not sure. Ran through those steps, but it felt strange with the small .357 cases. Maybe I haven't developed enough rapport with the pistol cartridge.

Walkalong, could be, but would be loader (as in me) error as I did the trimming and chamfering.

 

[Walkalong]

Shouldn't be that then, just adjust it down a hair at a time until shaving goes away. Be careful to start the bullets straight, whether you have a sleeved seater or not.

 

[9mmepiphany]

Is there any contact between the case mouth and the die body as it enters the Seating die?

You mentioned that you are using RCBS dies, on which press?

I don't think you mentioned who manufactured the bullet, or are these cast at homes?
Which size are you sizing them to?
Are you coating them?

 

[Mixed Nuts]

Walkalong, I'll try to refine my teqnique. On the whole there was very little shaving, but I did flare.

9mmepiphany, I'm using a lee hand press, and experience and some high road advice has made me careful to keep the brass seated against the back of the shell holder or risk case mouth problems.

Using cast performance, clear lube, 158 grain LSWC bullets. They come sized, but you know that.

 

[Walkalong]

Is there any contact between the case mouth and the die body as it enters the Seating die?

Good question, I have seen seater bodies so tight they reduce the flare on the case before it gets to the bullet when seating.