• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

6BR neck expansion die and mandrels

JackWagon

I have been fighting neck tension in my lapua brass. I tried the oversize expander ball's from Forster and even after annealing I still get inconsistent neck tension I can actually feel when seating bullets so I guess I have to start turning necks but I am going to start with an expander die and move forward from there as my frustration has hit a peak. For what my rifle is (Howa, bolt lugs, locking lugs, bolt face and action face squared up and a Shilen alternut barrel) when I can get 5 pieces of brass right I can get some really nice .245 MOA groups but most of the time I will get a flyer or two spreading my group out to .5, .6.

Looking at the PMA expander die body and all they show on the website is 6mm for the mandrel and no chart for sizing but 21st century has multiple in .0005 increments. The rifle seems to prefer 1 thou neck tension.

Long winded way of asking which expander die's do you prefer AND which necking turning device?

It would be nice if the mandrel could be used for both but I am sure that is out of the question as everyone seems to 50.00 dollar you to death.....lol
 
Porter precision and dont look back. You can get the gauge pins from him in .0005 increments. Love mine
 
JackWagon said:
I have been fighting neck tension in my lapua brass. I tried the oversize expander ball's from Forster and even after annealing I still get inconsistent neck tension I can actually feel when seating bullets so I guess I have to start turning necks but I am going to start with an expander die and move forward from there as my frustration has hit a peak. For what my rifle is (Howa, bolt lugs, locking lugs, bolt face and action face squared up and a Shilen alternut barrel) when I can get 5 pieces of brass right I can get some really nice .245 MOA groups but most of the time I will get a flyer or two spreading my group out to .5, .6.

Looking at the PMA expander die body and all they show on the website is 6mm for the mandrel and no chart for sizing but 21st century has multiple in .0005 increments. The rifle seems to prefer 1 thou neck tension.

Long winded way of asking which expander die's do you prefer AND which necking turning device?

It would be nice if the mandrel could be used for both but I am sure that is out of the question as everyone seems to 50.00 dollar you to death.....lol
Click to expand...
Are you by chance using a SS pin wet system to clean your brass?
 
I use Norma brass, Redding die with the expander ball removed and a Sinclair type mandrel ( It's actually Australian, but fits the Sinclair holder). The Mandrel is .243. Gives me good consistent 2 thou tension.
 
Wellington said:
Are you by chance using a SS pin wet system to clean your brass?
Click to expand...
No sir, walnut media in one of the old midway tumblers I have replaced the motor for twice over the last 20 years....lol.

I may have found another solution. I already have a hornady bullet puller and 6mm collets. I was thinking I could use some pin gauges as mandrels and round off and polish the ends and clamp them in the collet.

Personally I think a lot of my issue is the brass. Not sure if I got seconds from Lapua or what is going on. When I first got them in the box I had 19 of them that would not even fit in my shell holder while the rest just slid in as normal. The rest weigh out within close to a grain. As a backup I ordered some Peterson on Sat so who knows, that may resolve my issue. The pin gauges are cheap and it never hurts to have another measuring device anyway. I also put the word in at my range for a few pieces of lapua to compare as that is the only brass I have right now for 6br.
 
fkimble@charter.net said:
Wet tumbling does 3 things:
cleans it very good
removes the carbon from inside the neck, this increases neck tension and reduces consistency
dings up the end of the case mouth, needs a mandrel run in to true mouth and requires chamfering

Frank
Click to expand...
I wet tumble so already discovered this. By the original statement, I thought wet tumbling did something extra special (bad) to 6br brass. Depends on how you prefer your brass and brass prep process.

NO need to sidetrack the OP's issue.
 
JackWagon said:
I have been fighting neck tension in my lapua brass.
Click to expand...
Not really. You're describing inconsistency with SEATING FORCES.
A lot of seating force is frictional and independent of TENSION.
The only thing seating friction variance 'hurts' is consistent seating depths (without intervention).
JackWagon said:
The rifle seems to prefer 1 thou neck tension.
Click to expand...
This is 1thou INTERFERENCE of cal, and plenty reasonable.
That interference is expanded with seated bullet bearing, and the neck spring back FORCE to this condition is your tension. The force would be described as force typically is; in pounds per square inch (PSI), if we actually measured neck tension(we don't).
Given the force provided by 1thou of expansion, a more precise adjustment to this is through area that the force would apply (inches). That is, adjust the interference length (sizing length) that springs back against seated bearing. You would be adjusting PSI of of hoop tension here, and it's best to do with load development.
 
Last edited:
Believe it or not Mike that makes perfect sense to me AND validates to a small degree what I see when measuring the neck both before and after seating a bullet and part of the reason it's driving me nuts. I am getting .0008 tension by measurement BUT I can feel way to much feedback from my press arm and getting inconstant seating depth. On my 6.5CM and .308 I have the same .0008 by measurement but when seating they just glide in real smooth. ( I have custom dies for both those) My intent is to get my 6br brass right where I want it and then order a custom FL sizer. Trying to get to that point seems to be a major challenge but then again, I am by no means a genius.

I am really hoping the Peterson brass I ordered does the trick and yes, I plan to start neck turning if this does not get me exactly where I want to be.

For years everyone kept telling me. "get a 6br they are so easy to load for"
 
I am far from an expert regarding neck tension, but I think a lot of what you are experiencing with seating bullets is friction. I had the same issue with Dasher brass (Alpha). I use corn comb media in a vibratory tumbler. I use a Whidden FL bushing die with the expander ball removed and a bushing that undersizes the neck by about .003". Then I finish to .001" neck tension with a mandrel. This process also gave me a lot of variation in the force required to seat a bullet.

What I've started doing is brushing the inside of the necks, by mounting a worn 30 cal. brush in my drill press and running the neck up and down twice. I do this before I finish size with the mandrel. The process does not remove all the carbon from the necks, but it seems to give them a more consistent finish, which results in a much more consistent "feel" when seating bullets.
 
Well, for all the worry & resources you could spend on this, a couple kernels of powder one way or another might solve enough. Full seating testing usually solves a lot. Primer testing/striking can fix a lot.
Advanced reloading only works AFTER basic reloading.

If your seating forces obviously vary, but you measure each round and followup to set each at tested best CBTO, then a friction variance to seating(if that's the cause) makes no difference.
Best way to combat his is to leave the carbon layer inside necks alone.
If the cause is thickness variance, then you can measure this with a ball mic and cull out offenders.
If the cause is brass hardness, you can process anneal and minimal size to fix it.

If you normalize these items, taking all to standard, THEN you can expect seating force variance to comparatively indicate tension variance. Of course you can't do anything about that if seating bullets to discover it. That's where mandrels can provide one of their benefits. Mandrels can be used in a pre-seating operation, and show you things before seating actual bullets. This, giving you an opportunity to act on it.

I've been using mandrels for primary expansion, and as a pre-seating operation, long before mandrel use was cool. And a long time ago I did testing with various sensors and software to see what was going on.
I also decided a long time ago that I would develop a direct hoop tension measuring rig. But I just never got around to it...
What I settled on is basic reloading really (sound load development), and matching of pre-seating forces in normalized neck conditions. I stopped at load cell sensing inside a Sinclair expander die, feeding a basic meter circuit. With this, I'm confident that I see tension variance, and I adjust this to matching through neck sizing LENGTH. The interference I typically run with is 1thou, with a bushing, Wilson die, and never a length of sizing exceeding seated bullet bearing.
So before I seat actual bullets, I know their seating forces are matching all others, and I still check CBTO with every round, as that still needs sneaking into here & there.
My annealing, is dip annealing. I don't do it very often, don't need to, as my sizing is always minimal.
Seating force.jpg
 
SPJ said:
They ARE easy to load for. The only trouble i ever have had was trying to use too light or not enough bullet hold and the results were inconsistent grouping on paper.
You dont need mandrels except to round the mouth of virgin brass.
Get a bushing die with a selection of bushing sizes, I start with .003 under a loaded round.
Leave the carbon inside the necks, light brush prior to seating.

Get a grip and let Er rip
Click to expand...
Already have a Forster with .266, .267 and .268 bushings. That was my first stop and frankly, I am leaning toward I got a bad batch of brass which is why I ordered some Peterson
 
Bad batch of Lapua? Possible, but unlikely to cause seating force variance.
Going back to this original problem, have you annealed?
How much is your sizing? Fired neck OD -vs- loaded neck OD?
Neck friction condition?

Brand isn't going to matter.
 
Every time someone posts about neck tension, I get confused. Seems everyone has a different opinion on the subject. Bushing dies, neck expanders, neck turning, cleaning methods and mandrels to name a few. I think I am getting a headache!!!!
 
JackWagon said:
I may have found another solution. I already have a hornady bullet puller and 6mm collets. I was thinking I could use some pin gauges as mandrels and round off and polish the ends and clamp them in the collet.
Click to expand...

That’s what I use.

To put the taper on the pin gauge I turn the pin gauge in a drill against a belt sander
 
Reamer neck is too tight, necks need to be turned.
You were correct in your original post @JackWagon
Not your fault it's probably a bad reamer spec or an old warn-down reamer.
6BR is not this complicated.
How is this on page 2 already w/o someone pointing in this direction?
 
You must log in or register to reply here.

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Classified Ads

Forum statistics

Threads
166,241
Messages
2,214,577
Members
79,487
Latest member
Aeronca

Share This Page

Back
Top