6 Dasher - Neck "belling" out...*update* 6 Hydro Form Die Results

[bsumoba]

So with Lapua blue box 6BR brass, I use a .25 cal expander mandrel and necked up the brass. I then turned about 3/4 of the neck to 0.012" neck thickness. I used a Redding 6 Dasher competition bushing die with a .264 sinclair nitride bushing to then neck it back down to 6mm with 2-3K neck tension (I tightened up the top of the die so there is no play in the bushing). Once I get my barrel chambered, I will figure out how deep to go for the false shoulder.

However, I noticed I am getting a "bell" at the tip of the neck. I saw a few pictures of guys doing this and saw a slight bell as well, but did not know if this is normal. Is this an issue? Am I doing something wrong? Normal?

 

['Freak]

Re: False Shoulder 6 Dasher - Neck "belling" out?

Lookin’ like the case mouth done kissed the ceiling, for lack of headroom???

 

[ShootDots]

Re: False Shoulder 6 Dasher - Neck "belling" out?

So with Lapua blue box 6BR brass, I use a .25 cal expander mandrel and necked up the brass. I then turned about 3/4 of the neck to 0.012" neck thickness. I used a Redding 6 Dasher competition bushing die with a .264 sinclair nitride bushing to then neck it back down to 6mm with 2-3K neck tension (I tightened up the top of the die so there is no play in the bushing). Once I get my barrel chambered, I will figure out how deep to go for the false shoulder.

However, I noticed I am getting a "bell" at the tip of the neck. I saw a few pictures of guys doing this and saw a slight bell as well, but did not know if this is normal. Is this an issue? Am I doing something wrong? Normal?

Brian, when I do mine, I neck UP TO 6.5mm and turn the case necks A-L-L the way down and slightly into the shoulder. When you expand that far up, virtually any case neck imperfections are pushed to the outside and thus turned off. Then I place a .100K shim under my 6mmBR sizing die and run the cases back up in there. This creates a VERY DISTINCT false shoulder. NOTE: BEFORE you neck back down, place a "decent" chamfer on the OUTSIDE of the case mouth. This aides in sliding that case back up into the smaller (6mm) die. Then I anneal the brass and load it for fireforming. I believe what I am seeing from the pic you took, is you only went up to .257 and then back down to .243. There was not much decrease in neck sizing and I THINK that is what you are looking at. Additionally, I don't see an outside chamfer>>>that also could be part of the "problem"..

If you have a 6.5 sizing mandrel give that a shot. If it still looks a bit "bellied" rather than how it should look, you are doing something else I am not aware of..

 

[dmoran]

Re: False Shoulder 6 Dasher - Neck "belling" out?

When I first started using a false-shoulder method I to used a 257 expander, then later switching to a 6.5 expander. I find the 6.5 holds makes a firmer shoulder to "crush" against and yields both longer and more consistent brass for me.
I also turn the necks all the way to the shoulder. I like to have .020" to .030" crush to false shoulder against on bolt closer.
Adding a reference picture of my way:
Donovan

 

[jrm850]

Re: False Shoulder 6 Dasher - Neck "belling" out?

I don't know what causes that bell, but I've noticed it before on my brass too. It looks like one of Donovan's images shows some too.

 

[jamesl]

Re: False Shoulder 6 Dasher - Neck "belling" out?

Bryan I also use a 6.5mm mandrel and had the belling as well. I figured it was case spring back so I started annealing after I expanded and it solved my belling problem.

James

 

[bsumoba]

Re: False Shoulder 6 Dasher - Neck "belling" out?

I couldn't turn all the way down because my cutter gets in the way of the shoulder that my brass stops on. I can probably adjust the cutter, but I got lazy.

I measured the cut that I turned on the brass is enough to turn the whole finished 6 dasher neck (relative to my reamer spec) plus jut a tad more into the neck/shoulder junction so I called it good.

Before leaving for work, I took one that I did and chamfered it a little. That helped.

I will do another one today and chamfer before sizing it down to 6mm. I will let you know the results.

I bought the .25 cal expander and turning mandrel and if there is "bell-ing" on the 6.5 also, then I will probably stick with the 25 cal since I already have it. My neck is .271, so it will probably just work. I only have 1.5K on each side calculation wise to jam the false shoulder into the chamber for a "tight" fit.

 

[bsumoba]

Re: False Shoulder 6 Dasher - Neck "belling" out?

finished 100 pieces...now the wait for my chambered barrel so I can finish figuring out the depth for the resizing back to 6mm. Then, the debate of whether to shoot bullets or to COW.

I might even neck them further down and put them in a hydro forming die. :

 

[Phil]

Re: False Shoulder 6 Dasher - Neck "belling" out?

Bryan,

They will come out short in a hydro die, at least mine did.....

How far out is Marc with your barrel???


Phil.

 

[DJSBRS]

Re: False Shoulder 6 Dasher - Neck "belling" out?

Caution!

Turning necks all the way down prior to fire or hydro forming will have some risks of the shoulders being too thin and weak after they unfold from 6BR then refold to Dasher or BRX (inside).

Lapua has not designed this brass for making Dashers or BRX. Therefore it gets thinner at different points as you reform for larger case capacity.

Stretching or pushing that much forward or backwards has some risks. See attached.

DJ

DJ's Brass Service

 

[bsumoba]

Re: False Shoulder 6 Dasher - Neck "belling" out?

Caution!

Turning necks all the way down prior to fire or hydro forming will have some risks of the shoulders being too thin and weak after they unfold from 6BR then refold to Dasher or BRX (inside).

Lapua has not designed this brass for making Dashers or BRX. Therefore it gets thinner at different points as you reform for larger case capacity.

Stretching or pushing that much forward or backwards has some risks. See attached.

DJ

DJ's Brass Service

I was worried about this, which is why I did not turn them all the way down. I went as far down where I expect the neck/shoulder junction to be to get more even brass thickness. I also did not turn them all the way down. I only did a cleanup to max .012" brass thickness and found that it did about a 80-90% cleanup on the brass.

 

[DJSBRS]

Re: False Shoulder 6 Dasher - Neck "belling" out?

Lapua didn't help when they went from gold box to blue box and reducing the necks and case wall thickness down.

As you can see, the inside fold creases on this brass, it just another weak point. The new and old brass will always burst in the crease fold when forming out.

See the creases in this picture. All new brass has an inside crease folds when it is folded in to make the shoulder.

 

[dmoran]

Re: False Shoulder 6 Dasher - Neck "belling" out?

DJSBRS -

Great pictures and warnings...... Thanks for taking the time !.!.!
But at the same time I feel the need to say, from all my years of cutting necks (6BR, 6Dasher) to the shoulder I have never seen or experienced what you have. And have never heard anyone else complaint of such an issue either.
Best of Luck resolving the issue,
Donovan

 

[Jay Christopherson]

Re: False Shoulder 6 Dasher - Neck "belling" out?

Lapua didn't help when they went from gold box to blue box and reducing the necks and case wall thickness down.

As you can see, the inside fold creases on this brass, it just another weak point. The new and old brass will always burst in the crease fold when forming out.

See the creases in this picture. All new brass has an inside crease folds when it is folded in to make the shoulder.

Wow, I wonder how much brass was removed on those turns. Good cautionary though.

 

[shoot4fun]

Re: False Shoulder 6 Dasher - Neck "belling" out?

Lapua didn't help when they went from gold box to blue box and reducing the necks and case wall thickness down.

As you can see, the inside fold creases on this brass, it just another weak point. The new and old brass will always burst in the crease fold when forming out.

See the creases in this picture. All new brass has an inside crease folds when it is folded in to make the shoulder.

Wow, I wonder how much brass was removed on those turns. Good cautionary though.

I supplied the brass in the pics to DJ. It is blue box lapua and HAS NOT been turned. I have a fire-form barrel chambered with the same reamer as my match barrel and this brass was formed using the false shoulder method. My chamber is a .271 no turn that was designed around the blue box's thinner neck. I necked up with a 6.5 expander mandrel, then ran the brass thru my Redding Comp neck die with a proper bushing to form the false shoulder at the point where my bolt closed with slight efffort. They were loaded with a moderate charge and 70 grain Noslers for fireforming. The formed brass was then annealed and fired once in a match using 32.7 grains of Varget, 105 Hybrid and CCI450. They were annealed again and loaded for another match. It was at the third loading the splits showed up. It was not in every case from the box of brass but obviously they split where the old neck-shoulder junction of the original 6BR brass.
I shot that brass again this past Saturday without any further cases showing the signs of splitting.
Over the years I have formed a lot of Lapua 6BR into 6 Dasher. Until now, I have never had an issue.

 

[ridgeway]

Re: False Shoulder 6 Dasher - Neck "belling" out?

I bet annealing the new brass again would have helped tremendously.

 

[shoot4fun]

Re: False Shoulder 6 Dasher - Neck "belling" out?

I bet annealing the new brass again would have helped tremendously.

I annealed after not only fire-form but each firing of the brass. How much more annealing could I have done?
I use a Bench-Source machine for annealing. I have tried to make a habit of annealing before each reload.
I do that with my 6BR match rifle too.
Brass is also SS media tumbled.

 

[ridgeway]

Re: False Shoulder 6 Dasher - Neck "belling" out?

I bet annealing the new brass again would have helped tremendously.

I annealed after not only fire-form but each firing of the brass. How much more annealing could I have done?
I use a Bench-Source machine for annealing. I have tried to make a habit of annealing before each reload.
I do that with my 6BR match rifle too.
Brass is also SS media tumbled.

I was referring to annealing NEW 6BR prior to the hydro form. The failed cases that happen during a fireform are usually a slit or fold in the brass. Nothing can be done with those. Just can em and move on. At least this has been my experience messing with the Dasher since '09. I've never experienced anything remotely like DJ posted. Could be specific to hydro forming and different way of creating pressure. A nice load of varget and a 107 seem to make pretty nice cases...

 

[coford]

Re: False Shoulder 6 Dasher - Neck "belling" out?

I am using a .25 caliber expander but have tried .264 also and still had the problem. I could not figure out the reason for the belling but it bothered me (even though the cases looked fine after they were fired).

I messed around until I solved the problem by switching to a full length Forster die to size the neck back down instead of a bushing die. For what ever reason the bushing die was causing my problem. Your results may vary.

 

[bsumoba]

Re: False Shoulder 6 Dasher - Neck "belling" out?

I am using a .25 caliber expander but have tried .264 also and still had the problem. I could not figure out the reason for the belling but it bothered me (even though the cases looked fine after they were fired).

I messed around until I solved the problem by switching to a full length Forster die to size the neck back down instead of a bushing die. For what ever reason the bushing die was causing my problem. Your results may vary.

This sounds right. I remember another shooter I compete against telling me to use a FL regular die, not a bushing die.