Neck tension control
- Thread starter Oldmauser
- Start date
The case head separation would come more likely from over sizing/working brass (bumping shoulder to much etc). Just guessing softer brass would also contribute as the separation is caused by brass flowing from the case head towards the case neck.
If you have used brass checking for case head separation can be done by using a bent paperclip to check for the line where the case would fail near the head. You don’t want to use the case until it fails from case head separation no matter if you anneal or not. Can damage the gun and will end your hunt or range session on the spot.
I know a guy who got one in a Thompson Center single shot rifle. He went after it with pliers and a flat head screwdriver. He replaced his barrel after that failed bubba attempt to get the rest of the case out
As stated above your primer pockets would be one to start going most likely if your doing minimal sizing on your brass.
I have had primer pockets go on some hornady cases I loaded for my BIL gun. Haven’t been lucky enough to get case head separation yet. But I mostly run Lapua brass
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CHS also comes from brass flow under pressure and from the initial fire forming. A case initially fired from an oversized chamber will chs a lot sooner than one that was fired in a tight chamber even with subsequent minimal shoulder bumping. Also, the higher the pressure the more the case stretches the more the case walls thin out.
To clarify, I meant you won't overwork the caseneck/shoulder if you anneal each time. Thus no split necks and things, most likely failure would be case head separation or yes primer pocket failure. Sorry was tired and couldn't sleep last night cause I thought I kept hearing my little ones sneaking a peak on Santa... Merry Christmas everyone. 
I also use the Lee collet/ Redding body die for all my rifle calibers.
Affordable, reliable, repeatable and easy.
I do the body die first.
If you anneal often or every loading shoulder and neck sizing effects are greatly reduced.
I anneal every forth load but I do size the case minimally.
I heard today an "interesting" advice from a guy I met at the range: why don't you screw up your FL sizing die and size only the neck part (ca. 4mm), so you will get the proper neck tension and you won't lose the benefits of a fireformed brass at the same time.
Does it make any sense to you? What about a shoulder bump? This method would totally skip the shoulder bump...
Does it make any sense to you? What about a shoulder bump? This method would totally skip the shoulder bump...
All of your top shooters will be FL sizing. Bumping the shoulder back. Usually .002 ish. I do both fl and neck only depending what I’m shooting. My fclass comp gun gets fl every time. That’s the most consistent
Can you explain what FL sizing means to you? When I hear to Eric I think he meant by that something else than standard use of a standard FL sizing die. Do you just FL size all the way down the whole brass or you just bump the shoulder back?
You can’t use a full length die without sizing the whole body if it’s touching the case in. It’s in the name, full length. It’s going to touch the diameters no matter what. If it doesn’t then send that piece of shit die back because its mislabeled or miscut.
What you can do co from how much the shoulders get set back just enough to create reliable clearance in your chamber which is the .002 you seem brandied about. Or you can size it all theway back to saami minimum case specs if you’re sloppy with it.
But what you hear with full length sizing vs bumping shoulders aren’t two separate things, they are different degrees of the same thing.
You are right. It seems that the friendly advice to screw up the FL sizing die to achieve neck sizing only does not make much sense.
Yep, and with it up a smidge and the diameters still getting squeezed you will find that the shoulder actually moves forward, like a play dough snake when you roll it thinner it grows longer unless the die shoulder is there to stop it.
But if your cases aren’t fully grown to the full chamber size yet backing the die up and not moving the shoulder back can be helpful in achieving full form in the next firing. You just have to ensure that they still chamber after you size like that (like you always should). So as with everything there are degrees to it all and hard rules are meant to be broken.
Understanding and paying attention to your measurements is the key to happy loading.
When you run a fired case into a FL die, the first thing that gets sized is the body, not the neck. The die sizes the case walls and the shoulder pops forward which increases the shoulder length. You have to size the neck and bump the shoulder back down otherwise you won’t be able to close the bolt. In so doing you are sizing the body and the shoulder and the neck, essentially FL sizing 99% of the case.
Additionally size the neck? I don’t see what you mean.
Generally on a non bushing or non honed full length die the neck gets sized down more than necessary to ensure that even the thinnest brass is still effected. The expander ball that’s in the die then gets drug back through the now smaller neck and opens it to the proper internal size. Some skip the ball in the die and do a separate additional step and use an independent expanding mandrel to opens the necks to the exact desired internal size.
Generally on a non bushing or non honed full length die the neck gets sized down more than necessary to ensure that even the thinnest brass is still effected. The expander ball that’s in the die then gets drug back through the now smaller neck and opens it to the proper internal size. Some skip the ball in the die and do a separate additional step and use an independent expanding mandrel to opens the necks to the exact desired internal size.
@spife7980 I mean after FL sizing the brass many people (see this thread above) do the expander die with a mandrel to open the neck to a certain pre-defined diameter. Is it necessary in precision reloading? this is my question.
Necessary? No. But the mandrel is the most consistent means to getting necks the same.
Using just a die can leave the necks too small and with the thicker parts pushed for their inside than the thinner.
The expander ball takes care of that too small and irregularities but they are generally small so they don’t touch all of the neck at once and they are on a thinner rod and can be pushed off center a smidge with the brasses natural resistance to sizing.
The mandrel is big and the entire necks gets put onto the same rod all at the same time for a long dwell time and can’t really be pushed off center so easily. It’s just a more consistent method overall, it just takes 2x as many pulls of the press handle on a single stage press to use them.
From a mechanical point of view, pushing a mandrel down the neck results is a straighter neck ID for bullet seating because the case is supported squarely by the shell holder. It can’t move from side to side. Imagine a pyramid or cone with something pushing on the tip straight down. The base provides solid support and the thing won’t move. Any irregularities in the neck conform to the mandrel.
Pulling an expander ball through the neck is less desirable because the case is not supported and can wobble around as the ball passes through the neck. Any irregularities in the neck control the movement of the expander ball as it passes through.
Pulling an expander ball through the neck is less desirable because the case is not supported and can wobble around as the ball passes through the neck. Any irregularities in the neck control the movement of the expander ball as it passes through.
I know this is an older thread, but still have an issue. My problem is new Lapua brass run over a mandrel. Just starting my load development. 18 cases checked with a pin gauge to confirm all sized to the same inside diameter. Using a Wilson seating die and a arbor press no gauge. All cases were deburred inside mouth chamfer. Still had a few cases that took way less effort to seat the bullets than most of the others. I'm stumped. Hornady A-tip bullets. Any help would be greatly appreciated. Have not shot them yet.
I was hoping to avoid brass issues by using premium brass. The test will be when I go shoot it. Along those lines I have 200 rounds of this new brass. Should I shoot them all before annealing and sizing the once shot brass?
I know this is an old post but what do you personally consider over stretching of new brass, at the shoulder, on the first firing. Thx
Shoot them. Proper care and feeding after that will pay off by the 3rd firing in my experience.
Lapua makes consistent brass, but consistent doesn’t mean exactly the same. Virgin brass shouldn’t shoot bad, but it’s a pretty safe bet it’ll be better once it’s been fired 2-3x and has all been through the same routine a couple times... just don’t skip any steps, treat the cases the same every cycle and you’ll feel it at the handle and see it on target.
Lapua makes consistent brass, but consistent doesn’t mean exactly the same. Virgin brass shouldn’t shoot bad, but it’s a pretty safe bet it’ll be better once it’s been fired 2-3x and has all been through the same routine a couple times... just don’t skip any steps, treat the cases the same every cycle and you’ll feel it at the handle and see it on target.
On my 6.5 cm the factory hornady match ammo brass grows .003 -.0035. Virgin Alpha brass grows .0045-.005.
sorry if this is silly, but did you shrink the neck anyway with a FL or a neck die before applying the mandrel step? new brass is new brass, just freshly annealed in case of Lapua, but you can't trust them...ID will not be consistent, at best.
No I did not size the case or neck. I did however check the ID with a pin gauge and all were .002 under the bullet diameter. All felt the same with the pin gauge.
After further review it looks like several of the cases are over .262 ID. Used my pin gauges again and found almost all would take the .293 pin gauge and some even took the .2935 pin gauge. Think I will neck size the brass down to .261 then use the mandrel to expand out the neck hopefully with spring back to .262.
Here is my process for determining my bushings and mandrels:
This is for 0.308. I use either a 0.306 or 0.3065 mandrel. I want 2 thousands tension so the average neck size is .337 and I run a .335 bushing. To determine this I measure the neck wall thickness at four points then average it and divide by 2 then add the diameter of my bullet, IE .308. So 0.02921 + 0.308 = -.33721. After all is said and done I get .3345 -.335 Neck OD and .3045-.305 Neck ID. When bullet is seated I measure a .337 ish neck OD
| Neck Tension | |||
| 0.0141 | 0.01475 | 0.01505 | 0.01435 |
| Total | 0.05825 | ||
| Average | 0.0145625 | ||
| Thickness | 0.029125 | ||
| OD | 0.337 | ||
| 0.0145 | 0.0147 | 0.01435 | 0.0147 |
| Total | 0.05825 | ||
| Average | 0.0145625 | ||
| Thickness | 0.029125 | ||
| OD | 0.337 | ||
| 0.01455 | 0.01445 | 0.01485 | 0.0146 |
| Total | 0.05845 | ||
| Average | 0.0146125 | ||
| Thickness | 0.029225 | ||
| OD | 0.337 | ||
| 0.0148 | 0.01475 | 0.0145 | 0.0147 |
| Total | 0.05875 | ||
| Average | 0.0146875 | ||
| Thickness | 0.029375 | ||
| OD | 0.337 | ||
| 0.0146 | 0.0148 | 0.0147 | 0.0143 |
| Total | 0.0584 | ||
| Average | 0.0146 | ||
| Thickness | 0.0292 | ||
| OD | 0.337 | ||
| Overall | |||
| Average | 0.014605 | ||
| Thickness | 0.02921 | ||
| OD | 0.33721 | ||
| Bushing | 0.335 |
This is for 0.308. I use either a 0.306 or 0.3065 mandrel. I want 2 thousands tension so the average neck size is .337 and I run a .335 bushing. To determine this I measure the neck wall thickness at four points then average it and divide by 2 then add the diameter of my bullet, IE .308. So 0.02921 + 0.308 = -.33721. After all is said and done I get .3345 -.335 Neck OD and .3045-.305 Neck ID. When bullet is seated I measure a .337 ish neck OD
