Case mouth belling after FL sizing

[DiRTY DOG]

My case mouths are slightly belled out after FL sizing with the expander button assembly. There's a lip all around the mouth that catches when trying to close the bolt. Usually the bolt won't move forward completely without a good shove forward. Fired brass is ejected without the mouth belled out.

6.5x47L
Lapua brass (now 2x fired)
Mighty Armory FL sizing die with decapping rod & expander
RockChucker press

My process for fired brass:
1. Anneal
2. Lube inside neck with Imperial dry lube
3. Lube outside with Imperial wax
4. FL size with the expander, 2 thou shoulder bump measured with comparator
5. After that I trim/chamfer... New brass was below trim to depth and still is now.

Cases exit the FL die with the case mouth flared out. This happens without any trimming or chamfering. Straight out of the FL die.

If I remove the decapping/expander assembly, and FL size fired brass, the mouths are NOT flared out. The mouths are only belled out when using the decapping/expander assembly.

I'm puzzled and have never seen this before. What am I doing wrong?

 

[agr516]

Is your de-capping assembly screwed in too far and your case hitting that tapered portion at the top?

 

[shoot4fun]

You are tumbling instead of vibrating for cleaning. Likely using SS media as well.
I ran into this and, after a call to someone's tech support, the issue is peening from tumbling.
After cleaning and annealing I now chamfer case mouths. It will cure this issue.

 

[RustyInBend]

I had this issue until I ditched the expander ball and switched to mandrels.

 

[rwj]

You are tumbling instead of vibrating for cleaning. Likely using SS media as well.
I ran into this and, after a call to someone's tech support, the issue is peening from tumbling.
After cleaning and annealing I now chamfer case mouths. It will cure this issue.

I tumble using SS media and do experience some case mouth peen marks… never witnessed flaring as shown in the OP’s pics.

 

[urbanrifleman]

Is your de-capping assembly screwed in too far and your case hitting that tapered portion at the top?

 

[WillyTP]

Is this a bushing type sizing die?

 

[DiRTY DOG]

Is your de-capping assembly screwed in too far and your case hitting that tapered portion at the top?

No, the assembly is fixed, it's not possible to adjust it at all.

 

[DiRTY DOG]

You are tumbling instead of vibrating for cleaning. Likely using SS media as well.
I ran into this and, after a call to someone's tech support, the issue is peening from tumbling.
After cleaning and annealing I now chamfer case mouths. It will cure this issue.

Wrong. I listed my exact loading process above.

With NO tumbling, NO vibrating, NO trimming, and NO chamfering, a fired case exits the FL sizing die with the case mouth flared as shown and described.

 

[DiRTY DOG]

I tumble using SS media and do experience some case mouth peen marks… never witnessed flaring as shown in the OP’s pics.

There was no tumbling or vibrating involved.

 

[DiRTY DOG]

The case does not reach that height on the decapping stem, it's not possible.

 

[DiRTY DOG]

Is this a bushing type sizing die?

No.

 

[Dusty Stevens]

Its sizing the neck too much

 

[WillyTP]

No.

Another question. When you use the expander assembly what size is your finished neck diameter versus without it? The relationship between how much the die makes your neck and the expander makes it is too severe.

 

[WillyTP]

Its sizing the neck too much

Jinx you owe me a coke, see you this weekend and we can settle up lol.

 

[Dusty Stevens]

Jinx you owe me a coke, see you this weekend and we can settle up lol.

Youre my man still for sure

 

[L1986]

The case does not reach that height on the decapping stem, it's not possible.

Can it reach this part of the die?

 

[Rocketvapor]

Is the case neck going above the neck sizing zone of the die.
Not the stem but the die body.
Like maybe the trim length is too long for the die body?

 

[DiRTY DOG]

Can it reach this part of the die?

Not even close.

 

[MSS]

Have you looked inside the die? Maybe it’s milled incorrectly in the neck area so when the expander ball pushes the case against the die wall it flares. This would not happen when the expander is not in use.