crushing case necks when using expander mandrel to open case neck on a 338SS

[MAD10]

Just to give a visual for all viewers … the neck totally pancakes when a piece does give way and collapses …

interesting enough the actual neck OD is exactly the same as a neck that fully expanded and the shoulder didn't fail

** in this pic the .338 mandrel is hand seated in a fully expanded neck that didn't collapse…that "witness mark" is there simply to show where the mandrel stops in relation to the neck when hand seated on either a fully expanded neck or one that collapsed

again no issue going from .284 to .308 it's only when going from .308 to .338 this occurs … it's got me baffled

honestly the only thing different in each step is the mandrel … might have answered my own question right there lol

 

[Tiny Tim]

Is it possible that the neck is work hardened from the first neck expansion step and is now beyond the yield point of the shoulder area? Could try annealing just the neck, or possibly modifying your .338 mandrel to have a more gradual entry taper. Perhaps try a different lube (I forget if you stated what type you were using).

 

[joelpend]

.338 is on the left .308 is on the right

You need a different mandrel when you are expanding up cases. They make longer mandrels with a much longer taper so the expansion is more gradual. Since I have a AMP I anneal often if I am forming wildcats.

 

[Mike6158]

It's not running in too far and striking the top of the mandrel is it? You're doing everything right.

This. I was doing something similar when I set the expander ball too high (trying to get it out of the way).

 

[Ross1147]

I had this issue when expanding my 338ss brass. I was using the first run stuff so 30 deg shoulder that still required fireforming. Anyway, I was crushing 1 in about 5 doing the 2 step .308/.338. So I picked up a .32 mandrel from brownells. Just adding that extra step solve my problem.

Ryan

 

[Vanden Berg]

338-06 is my preferred hunting caliber. When expanding necks from 308 to 338, I run an 8mm expander in them as an intermediate step. Has worked perfectly.

Hope this is useful.

 

[lancetkenyon]

The 40° shoulder is the problem (for necking up or down). Too much pressure on that 40° shoulder and it collapses.

I would be necking up in at LEAST 4 steps from .284 to .338. Probably even 5 or 6.

When I neck DOWN the 6.5SS brass (comes as slightly bigger than 7mm too) from 7mm to 6.5mm, I do it in 3 steps. With a .305, .297, amd .291 bushing. I lube necks at each stage.

 

[Tidesloe]

I ran into this with ADG brass from Rich earlier this week. When expanding 300 SS headstamped brass from 284 to 308. I have a Sinclair expander die and SS mandrels that need replacing. Can't seem to find carbide mandrels anywhere so I bought a full 30 cal mandrel set from 21st century innovations to try. It includes 9 mandrels from .304 to .309. I began with the smallest in the set at .304, and crushed 1 of my first 2 with Imperial dry neck lube. I then switched to Imperial sizing wax which made the sizing easier, but still crushed another one of my next 4 or 5. I had also bought from 21st century a 7mm to 30 cal neck up mandrel which has a much longer taper and with sizing wax had no more crush on me. I also have necked up 7mm to 338 SS in the past with no issues. I've never crushed necks before this week, but the only way I was able to get through a box of 300ss necked up from 284 was with a 7mm to 30 cal neck up mandrel with sizing wax. I wouldn't even try this mandrel with dry neck lube. This batch of brass is way too soft. That's the only conclusion I can come to on it

 

[Tidesloe]

Given the fact this brass seems to be soft brass or over annealed, I'm debating if I should re-anneal now after sizing. I've got an amp annealer with Aztec so I think I'd be ok if I sacrifice another case to run an Aztec analysis on the brass. I don't think it would over anneal it? What do you all think?

 

[K.E.C.]

Tag. I'm in.

 

[joelpend]

Given the fact this brass seems to be soft brass or over annealed, I'm debating if I should re-anneal now after sizing. I've got an amp annealer with Aztec so I think I'd be ok if I sacrifice another case to run an Aztec analysis on the brass. I don't think it would over anneal it? What do you all think?

You will not over anneal the cases by repeated annealing. This straight from the mouth of the AMP folks in New Zealand.

 

[Tidesloe]

I do believe I remember seeing that on their website. I'd still like opinions from guys doing it.

 

[MAD10]

I ran into this with ADG brass from Rich earlier this week. When expanding 300 SS headstamped brass from 284 to 308. I have a Sinclair expander die and SS mandrels that need replacing. Can't seem to find carbide mandrels anywhere so I bought a full 30 cal mandrel set from 21st century innovations to try. It includes 9 mandrels from .304 to .309. I began with the smallest in the set at .304, and crushed 1 of my first 2 with Imperial dry neck lube. I then switched to Imperial sizing wax which made the sizing easier, but still crushed another one of my next 4 or 5. I had also bought from 21st century a 7mm to 30 cal neck up mandrel which has a much longer taper and with sizing wax had no more crush on me. I also have necked up 7mm to 338 SS in the past with no issues. I've never crushed necks before this week, but the only way I was able to get through a box of 300ss necked up from 284 was with a 7mm to 30 cal neck up mandrel with sizing wax. I wouldn't even try this mandrel with dry neck lube. This batch of brass is way too soft. That's the only conclusion I can come to on it

we are certainly having the same experience….

it should be no problem going from .284 to .338 many including Rich say as much.
I agree with notion these cases being too soft … I also agree with another comment about the 40° shoulder being sensitive to crushing

the suggestion of an 8mm mandrel as a second step is sound

I tried using two different lubes imperial dry lube which I've always used and Hornady's unique either prevented the problem

Hoping the longer shaft and more gradual taper in the LE Wilson mandrel will reduce or eliminate the issue.

 

[MAD10]

I had this issue when expanding my 338ss brass. I was using the first run stuff so 30 deg shoulder that still required fireforming. Anyway, I was crushing 1 in about 5 doing the 2 step .308/.338. So I picked up a .32 mandrel from brownells. Just adding that extra step solve my problem.

Ryan

Yep makes sense … just ordered the 8mm (.325) mandrel