Why are these case necks collapsing?

[tjsudbury]

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I picked up some Norma 6.5x284 brass with the intention of making some high quality .284win brass out of it.
The problem is that when running it through the rcbs .284 sizer dies, the necks are collapsing, on one side, as shown above. One had mica for inside neck lube, one had Lee sizer lube, and the third had a small amout of imperial sizing die wax. All with the same result.
Norma brass is too expensive to be screwing arround with trying to figgure out the problem, and bumping the necks up from 6.5 to 7 mm isn't that big of a jump.
Any idea whats going on here?

 

[paperslayer]

the 7mm expander ball from the die is pushing on the case mouth and because the neck walls are not suppported (6.5 in a 7mm die), they are collapsing. You need to use an expander mandrel or fire form. This will not work.

 

[Bassmaster]

I'm just guessing.....obstruction in the die?..take the die apart, inspect, clean as required, re-assemble maybe??
That looks very strange and annoying all at the same time

 

[blaser.306]

I like using the Hornady eliptical expander when I am "stretching necks" I do 7mm TCU in one pass from .223 with no difficulty, but have found that the RCBS expander button can be a little tough on brass when doing re forming.

 

[paperslayer]

I'm just guessing.....obstruction in the die?..take the die apart, inspect, clean as required, re-assemble maybe??
That looks very strange and annoying all at the same time

i'm not guessing. It IS the expander ball.

 

[johnny88]

i'm not guessing. It is the expander ball.

x 2

 

[tjsudbury]

I'm thinking that expanding from 6.5 to 7mm shouldn't cause the necks to collapse like this, should it? Or is it that the RCBS button just doesn't work like some other brands of dies. People expand necks all the time without this happening.

 

['Boo]

The only problem is that you need a tapered expander ball.

 

[paperslayer]

Unless specifically tapered, expander balls are supposed to work as they are PULLED through the mouth of the case. In this case, the blunt shape of the ball combined with the lack of wall support (look at the wrinkle at teh base of the neck) Norma brass is too soft and too expensive to screw with doing it wrong

 

['Boo]

For what it's worth the Sinclair expander die with tapered mandrels are my favorite method of necking cases up.

 

[tjsudbury]

Unless specifically tapered, expander balls are supposed to work as they are PULLED through the mouth of the case. In this case, the blunt shape of the ball combined with the lack of wall support (look at the wrinkle at teh base of the neck) Norma brass is too soft and too expensive to screw with doing it wrong

You got that right. So my rcbs dies have the expander ball, I was just looking at thier website for tapered expanders, but they don't seem to have one for 7mm dies. What are my options without getting new dies?

 

['Boo]

If you have a set of RCBC dies in 270 you may want to take the ball off that and use it to replace the one on your 284 dies. That should open the necks up enough to accept your 7mm ball later.

 

[paperslayer]

Stick witht he same dies, bur get an expander die like boo says. they are about $35 from sinclair... just order the 7mm/284 EXPANDER mandrel (as opposed to the turning mandrel)

 

[tjsudbury]

If you have a set of RCBC dies in 270 you may want to take the ball off that and use it to replace the one on your 284 dies. That should open the necks up enough to accept your 7mm ball later.

I tried that, and that seems to work. Bumping them up from .264 to .277 doesn't look like its doing any harm. I expect that going from .277 to .284 won't either. Looks like problem solved. Thanks guys.

 

[joe-nwt]

Unless specifically tapered, expander balls are supposed to work as they are PULLED through the mouth of the case. In this case, the blunt shape of the ball combined with the lack of wall support (look at the wrinkle at teh base of the neck) Norma brass is too soft and too expensive to screw with doing it wrong

This.

 

[Cleftwynd]

I have noticed that Series B,C, or D from Redding all have the tapered button. at least in all the ones I have bought... nice idea! I use the tapered buttons for sizing brass from a different chambering, otherwise I use carbide buttons as then I do not have to lube the inside of my necks!

 

[bjmurata]

I've had my share of that stuff over the years when necking up brass from one caliber to another when using standard expander balls or buttons as found in standard die sets.Going up in gradual stages didn't always give me the kind of finished necks I was after and I ended up ruining lots of cases in the process.I solved my necking up woes by purchasing Tapered Expander Plugs by CH4D that are the greatest thing since sliced bread,in my opinion,for necking up operations when reforming from one caliber to another.You can purchase them direct from CH4D right over the phone,the last ones I bought only a short while ago were $15.22 each and they range from 22-24 caliber all the way up to 40-50.I purchased a couple of their Expander Die Bodies as well that the expander plugs go into.I'm really happy with them and they have made my reloading life a whole bunch more enjoyable.

 

[JJessup]

I've had my share of that stuff over the years when necking up brass from one caliber to another when using standard expander balls or buttons as found in standard die sets.Going up in gradual stages didn't always give me the kind of finished necks I was after and I ended up ruining lots of cases in the process.I solved my necking up woes by purchasing Tapered Expander Plugs by CH4D that are the greatest thing since sliced bread,in my opinion,for necking up operations when reforming from one caliber to another.You can purchase them direct from CH4D right over the phone,the last ones I bought only a short while ago were $15.22 each and they range from 22-24 caliber all the way up to 40-50.I purchased a couple of their Expander Die Bodies as well that the expander plugs go into.I'm really happy with them and they have made my reloading life a whole bunch more enjoyable.

Agreed.

 

[Bassmaster]

i'm not guessing. It IS the expander ball.

Thanks for clearing that up for me......