Different headspacing on different brands of brass??

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Different headspacing on different brands of brass??

Post by Rod_outbak » 05 Jul 2018, 8:49 am

I keep thinking the answer to this is right in front of me, but I cant think WHY...

I am in the process of loading up my second batch of reloads for the Ruger Precision Rifle.

From new, I bought 140 Buffalo River/OSA 135 HP rounds, and also ~800 Federal VitalShok 130Gn HP rounds, and have fired them all off.
All of this factory ammo has only been fired through the RPR.
All the OSA brass, and the first 200 of the Federal brass, have now been through the tumbler, and came out nice & clean.
All of the OSA brass was then FL sized, trimmed, checked for length, steel-wool on the case mouth, primer pocket uniformed, and inside brushed.

I then loaded up the OSA brass with 125gn SST's, and have been giving the local grasshoppers a lot of tragedy.
The OSA brass loaded up beautifully, and the brass seems really consistent.
As a final measure, I weigh all loaded rounds, and the OSA brass was all within ~2 grains of each other when weighed loaded.
Thats NOT a lot of variation!

So, over the next couple of days, I'll be moving onto the Federal brass. The first 200 cases have been de-primed, and cleaned, and so are about ready to be FL sized.

As part of my case-prep, I set up my headspace gauge on my calipers, and ran 5 of the Federal cases through the FL sizing, on my Forster Co-axial press.
This die was previously set for the OSA brass, and to push the shoulder back 0.0025".
So.....here's where I'm wondering if I'm just thick as a brick??
The FL sizer die was set to push the OSA brass shoulder back .0025". Each case was checked before (0.000"), and after (~ -0.0025").
So, when I check the 5 Federal brass cases, they have all consistently been pushed back 0.005".
[I took special note of the fact that ALL of the 5 Federal cases were pushed back exactly 0.005".]

How is it possible, when (as far as I know) the FL die is 'massaging' the outside shape of the brass, can they be noticeably different?
Is it to do with a different thickness of brass?
They were all fire-formed in the same chamber, and are being FL sized in the same die.

Is this a common thing??

It's no big deal, as I will simply adjust the die to give me a 'bump' of -0.0025".
And, I purposefully held off working on any of the Federal brass, until I had all of the OSA brass processed first, as I suspected I might run into something like this.
But it started me wondering why this might happen.
Are different brands of brass always going to be pushed back differently in the same die?
Is this something that will happen less with each reloading?

All these questions and more...

Cheers,

Rod.
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Re: Different headspacing on different brands of brass??

Post by Stix » 05 Jul 2018, 10:23 am

Sounds a strange one to me too Rod so im unable to help you :unknown: ...but im keen to hear the answer if & when you find it. :thumbsup:
I have some strange stuff happen on the press too sometimes, frustrating. :x

Im curious to ask, why have you decided to FL size all the brass after being fired in that chamber & not just neck size them...?
Were they tight to re-chamber ?
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Re: Different headspacing on different brands of brass??

Post by RoginaJack » 05 Jul 2018, 10:58 am

Left field - I had trouble getting 22lr shells to extract from a Sportco semi-automatic (not to be confused with a semi-semi-automatic) and turned out to be that the rims were different thickness between brands. Could that be on centre fire brass too?
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Re: Different headspacing on different brands of brass??

Post by No1_49er » 05 Jul 2018, 12:57 pm

Without knowing what cartridge it is that you are dealing with it's a bit difficult to give precise number.
If you go to https://saami.org/ and search for your case the dimensions are listed for pretty much everything.
A random example for 243 Win shows rim thickness of 1.37mm with allowance for that to be down to 1.12mm i.e. -0.25mm, which happens to be 10thou.
That might explain things?
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Re: Different headspacing on different brands of brass??

Post by Rod_outbak » 05 Jul 2018, 1:20 pm

[quote="Stix"]Sounds a strange one to me too Rod so im unable to help you :unknown: ...but im keen to hear the answer if & when you find it. :thumbsup:
I have some strange stuff happen on the press too sometimes, frustrating. :x

Im curious to ask, why have you decided to FL size all the brass after being fired in that chamber & not just neck size them...?
Were they tight to re-chamber ?[/quote]

Stix,
I FL sized them this time around, as I intended to check/trim them all to length.
[Not sure how long the OSA brass was, but it was all longer than the trim-to length for .308 cases, so they all got shaved.]
I wanted to start the cases off as uniform as I could make them, so figured I'd FL size them & trim them for the first reload, and from then on I'll neck size them, and bump them back if they need it.

Cheers,

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Re: Different headspacing on different brands of brass??

Post by Rod_outbak » 05 Jul 2018, 1:31 pm

[quote="No1_49er"]Without knowing what cartridge it is that you are dealing with it's a bit difficult to give precise number.
If you go to https://saami.org/ and search for your case the dimensions are listed for pretty much everything.
A random example for 243 Win shows rim thickness of 1.37mm with allowance for that to be down to 1.12mm i.e. -0.25mm, which happens to be 10thou.
That might explain things?[/quote]

Sorry; .308 Win cases.

I'm not sure why the rim thickness variation between brands of brass would cause them to be bumped back differing lengths in the same die, as the headspacing measurement was zeroed (using an average of 5 cases to set the zero) for each brand of brass before FL sizing the batch.
But I certainly dont have any other/better ideas at this point.

It just doesnt seem to make sense why the HS 'bump' is applied to the exterior of 2 cases, then why one brand would be consistently different to another afterwards.
Could one brand be more 'springy' brass??

A mystery so far.
No biggy; I'll just keep adjusting my dies before each batch [which I do anyway because I'm a pedantic bastard...]

Cheers,

Rod.
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Re: Different headspacing on different brands of brass??

Post by marksman » 05 Jul 2018, 8:36 pm

you can shave off some rim thickness with a wilson trimmer Rod
you just turn the case around backwards in the trimmer
it actually squares off the rim, I do it after the first fireform in some cases for that reason
not that I believe it is 100% necessary just I think if the bolt face is squared why not the rim?
you would not believe how much they can be out, some only touching by a quarter of the rim
put a square on your brass and see how much light will come through the gap
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Re: Different headspacing on different brands of brass??

Post by Gwion » 07 Jul 2018, 4:01 pm

marksman wrote:you would not believe how much they can be out, some only touching by a quarter of the rim
put a square on your brass and see how much light will come through the gap


Wouldn't that just show the case wall taper?

This topic has me buggered! I don't understand how case rim thickness would effect an headspace. The base of the case sits flush on the case holder and the bolt so the measurement to the shoulder should be consistent... :unknown:
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Re: Different headspacing on different brands of brass??

Post by Stix » 07 Jul 2018, 4:35 pm

He's not the only one...i get the same discrepancy & with same brand brass...
Ive never worked it out.
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Re: Different headspacing on different brands of brass??

Post by Rod_outbak » 07 Jul 2018, 5:38 pm

Stix,

I found a few articles on US forums, that confirm that different brands of brass for the same calibre/cartridge, WILL flow differently during sizing, due to differences in metal formulation, thickness, and hardness. So, it seems that it is a known consideration.
Maybe even the same brand can have this issue, if they are changing the composition of the brass between batches?
It took a lot of searching, as the same search terms return a lot of info about the merits of FL sizing and the importance of setting the headspace 'bump' adjustment correctly...
Talking to a mate who does a lot of shooting, and he'd had another shooting mate talking about the same issue over lunch.
Up until that discussion, my mate hadnt run encountered the issue.
But then I realise that he has a Giraud case anealer, so I'll have to ask him if that's why he hasnt run into it(have to ask him his annealing regime).

If you simply set your headspace adjustment to be large enough to 'bump' all brands of brass, you likely arent going to ever see the problem.
But for me, I'm wanting to only be bumping my shoulder back ~0.0025" or so, to minimise the amount of stretching on the cases.

Anyway, it's no big deal, really. I check my headspacing every time I size (Neck OR F/L) these days, and it doesnt take long to adjust the dies.

Cheers,

Rod.
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Re: Different headspacing on different brands of brass??

Post by Bills Shed » 07 Jul 2018, 5:55 pm

Gwion is on the money here, but I think Marksman would have the brass case in his Wilson trimmer and using a square on that. I understand the idea of squaring up the base but head space measurement does not change squared base or not. Rim thickness has nothing to do with the head space. In this case ( excuse the pun) headspace is from the face of the bolt / base of the brass to a point on the shoulder.

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Re: Different headspacing on different brands of brass??

Post by marksman » 07 Jul 2018, 7:35 pm

I hope this photo works out to show a case that the base has been squared
anyway I probably should have said to use a straight edge or as Bill said a square with the case in the wilson case holder

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Re: Different headspacing on different brands of brass??

Post by Stix » 07 Jul 2018, 7:41 pm

Well i can get .005" difference in the headspace measurement within the same batch of brass...i cannot understand it so i just figure its the POS hornady press i have.

I can get the bump perfect for a batch,, then get a run of 3/5 cases that still wont chamber & i have to adjust the die individually for.

Ive emailed hornady direct & they just give gibberish bullsh1t excuses claiming its the brass or (other brand) dies...
Ive challenged them on their answers but they just dont answer--i guess because they dont have an answer.

I was hoping for a miraculous answer to appear in this thread...
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Re: Different headspacing on different brands of brass??

Post by Stix » 07 Jul 2018, 7:48 pm

You're right marksman. :thumbsup: ..ive done just that on some cases for nothing more than exploritory reasons & i was blown away at how out of square some cases are...!!
But so far ive been sucessful in winning the fight against my OCD that wants me to square up all my case heads... :lol:

But i doubt its the reason i get such a variance in measurements.
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Re: Different headspacing on different brands of brass??

Post by straightshooter » 08 Jul 2018, 7:44 am

When you FLS you are performing a drawing operation.
Now consider that every case has a hardness gradient with the solid web being the hardest and the case neck the softest. The hardness determines the resistance to drawing and the amount of spring back when drawn.
Even with quality brass and the best and most careful use of lubricants and high quality dies I have been unable to get variations in head to datum measurements better than 2 to 3 thou over large numbers of cases measured.
So my conclusion is that you are at the mercy of the brass you have and there is no simple fix just the tedium of careful measurement and sorting.
Beat's me why you do any tinkering at all with once fired brass if you are reusing it in the same chamber it was fired in. All that should be needed is neck sizing and FLS only when chambering becomes difficult.
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Re: Different headspacing on different brands of brass??

Post by Stix » 08 Jul 2018, 9:12 am

I only ever FLS when brass becomes tight to chamber...or if im using once fired brass from a different chamber.

Maybe a stupid question straightshooter, but what do you mean when tslking of a "drawing operation"...?
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Re: Different headspacing on different brands of brass??

Post by Rod_outbak » 08 Jul 2018, 9:16 am

I'm 'tinkering' with once-fired brass, as I want to trim it all to a uniform length, and my first opportunity to do so, is after the first firing.
I'd prefer to do trim the brass AFTER I've FL sized it first.
What I'm doing, is before I load the once-fired cases for the first time, that I have them reasonably uniform.
Previous experience with reloading the Federal factory brass, was there was a significant variation in case length, when I measured cases after their first firings.

As I've said previously, I'm not intending to FL size the brass every time it's reloaded. However, the FIRST time I get the chance to work the brass (as these were factory loads in the first place), I would prefer to get them all as uniform as possible. SO, MY preference, is this first time, they all go through the FL sizing die, and then get trimmed to length. After that, they get neck-sized until I get chambering issues, or they've grown enough to require trimming again.
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Re: Different headspacing on different brands of brass??

Post by SCJ429 » 08 Jul 2018, 10:36 am

Drawing is a lengthening of the brass, any time you compress or squeeze the brass, as in sizing the brass lengthens. If you hammer metal you thin and lengthen it. This is what sizing does also, the object is to get the brass to the size you want without overworking it.

Marksman, when I square up the base of my brass, almost without exception it takes a little off one side. Do you do this to all your brass as part of your routine preparation?
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Re: Different headspacing on different brands of brass??

Post by straightshooter » 08 Jul 2018, 12:25 pm

Rod_outbak
Wouldn't it make sense then to just trim the fired case. A little play on the neck pilot shouldn't pose a problem. If it is a problem then neck size only and trim.
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Re: Different headspacing on different brands of brass??

Post by Stix » 08 Jul 2018, 1:21 pm

Hey Rod...obviously im no expert, but with the brass you have id not mess around with it after its formed, other than neck size, trim & chamf/D'burr...

(I read somewhere ages ago it was good to FL Size brass after first firing, but i find its just a waste of time & dont do it now because depending on how springy the brass is that might mean firing 300 rounds before i get a uniform batch of 100 pcs-fuk that...!).

So once my brass is formed i just do as i said above...with the exception that sometimes i find brass needs a second firing to fully form (im talking uniformly over an entire batch), so once thats done, my regime is a clean, primer pockets & flash holes, then in one night i do the production line thing & neck size, trim, vld chamf & de-burr & a big wet tumble & good rinse- to get it out the way, (so my hands look like ive just swapped out the diff on an old holden by the time the cases hit the tumbler).

From there i just neck size..i find the odd case may stretch ever so slightly from firing after that, but not more than a thou so i just leave em be untill too tight to chamber....
& i really dont fl sizing.
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Re: Different headspacing on different brands of brass??

Post by Stix » 08 Jul 2018, 1:27 pm

Thanks SCJ & straighshtr... :thumbsup:
I know the brass lengthens or (flows) through the process, but didnt know the term 'drawing'... :drinks:
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Re: Different headspacing on different brands of brass??

Post by SCJ429 » 08 Jul 2018, 1:55 pm

Sorry Stix, didn't mean to sound simplistic,

I would just fire the new brass once, trim them to length and select the ones that are closest in weight for your best brass. No need to keep firing them before batching. I saw a guy fire forming Dasher brass and it was shooting in the .2s during forming.

The tumbled clean brass will be very grabby, neck tension consistency is harder with clean brass. I would clean the outside necks with some oil or solvent on a rag and leave the inside with the carbon intact. You can even dip the necks in Imperial graphite if you are really keen.

Don't trim unless some of the cases have reached maximum and then trim them all in that batch.
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Re: Different headspacing on different brands of brass??

Post by Stix » 08 Jul 2018, 3:08 pm

You've nothing to be sorry for SCJ... :unknown:
I asked a question--you answered--thats appreciated...!! :drinks:

Now i know drawing is not just a form of art, or the term for part of the process in making a good cuppa tea, but also a term used for metals flowing through manipulation...!!

I rather hear 100 simplistic things & learn one, than hear & learn nothing...& sounds to me you've experience i can learn from :thumbsup:

Im pleased with your suggestions on brass regime...it is pretty much what i do so hopefully im on the right track.

I have to enter the realms of annealing & other dies to better my neck tension (scary)...but i shan't go there in this thread...

I just felt i should speak up on this one as ive encountered the same problem as rod... :unknown:

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Re: Different headspacing on different brands of brass??

Post by straightshooter » 09 Jul 2018, 8:01 am

Stix wrote:Thanks SCJ & straighshtr... :thumbsup:
I know the brass lengthens or (flows) through the process, but didnt know the term 'drawing'... :drinks:


Drawing has specific meaning as a term for a particular metalworking process.
Similarly other metalworking processes are described as blanking, stamping, pressing, forging etc.
Some terms may be familiar, some may not but nevertheless they all refer to fairly specific processes.
If you want to inform yourself then google the term " drawing brass cartridge cases" where I am sure you will find a wealth of information.
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Re: Different headspacing on different brands of brass??

Post by Rod_outbak » 09 Jul 2018, 11:46 am

[quote="straightshooter"]Rod_outbak
Wouldn't it make sense then to just trim the fired case. A little play on the neck pilot shouldn't pose a problem. If it is a problem then neck size only and trim.[/quote]

Straightshooter, I dont use a neck pilot when trimming.

Thanks for the suggestion, but I wasnt asking for advice on why I should/shouldnt FL size.
I just wanted to know if anyone had encountered the variation in headspacing.

It turns out that it is a known issue, so I did end up with an answer to my question.
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Re: Different headspacing on different brands of brass??

Post by Rod_outbak » 09 Jul 2018, 12:57 pm

[quote="Stix"]Hey Rod...obviously im no expert, but with the brass you have id not mess around with it after its formed, other than neck size, trim & chamf/D'burr...

(I read somewhere ages ago it was good to FL Size brass after first firing, but i find its just a waste of time & dont do it now because depending on how springy the brass is that might mean firing 300 rounds before i get a uniform batch of 100 pcs-fuk that...!).

So once my brass is formed i just do as i said above...with the exception that sometimes i find brass needs a second firing to fully form (im talking uniformly over an entire batch), so once thats done, my regime is a clean, primer pockets & flash holes, then in one night i do the production line thing & neck size, trim, vld chamf & de-burr & a big wet tumble & good rinse- to get it out the way, (so my hands look like ive just swapped out the diff on an old holden by the time the cases hit the tumbler).

From there i just neck size..i find the odd case may stretch ever so slightly from firing after that, but not more than a thou so i just leave em be untill too tight to chamber....
& i really dont fl sizing.[/quote]


Stix, thanks for the advice, but I wasnt asking whether I should FL size brass.
If the process you've detailed works for you, then Happy Days.
I was asking if anyone had encountered the variance in headspacing between brands of brass, and while no-one here has, it turns out to be well known elsewhere.
So I got my answer, eventually.
[On an aside, I read in 3 different articles this morning, that many competition shooters are returning to FL sizing every reload, so it seems that there are just as many arguments for and against it.]

For cartridges like my .243, .308, 7mm-08, I follow this regime:
- If fired, they get de-primed and cleaned in a wet tumbler. Wet tumbling cleans inside/outside case and primer pockets.
[If new & unprimed, skip the previous process]
Inspect cases and reject any obvious defects, and then either:-
a). For new brass to this rifle (new, once-fired factory, or from another rifle)
- FL size with headspacing adjusted to -0.0025" below fired cases for this rifle.
- Trim in Giraud trimmer, which also chamfers inside/out.
- Check case length is now Trim-To-Length minimum.
- Steel wool on case mouth to remove any residual burrs. (Use battery screwdriver)
- Primer pocket uniform tool. (Use battery screwdriver)
- Inside Nylon case brush to ensure insides have nothing stuck within (Use battery screwdriver)

b) For cases I have previously loaded,
- de-prime and tumble clean.
- Once dry, inspect, and discard rejects
- Check case-length, and check if headspace allows the bolt to close easily.
- If above max, then start on process a).
- If below max, Neck-size.
- Chamfer inside/out (using battery screwdriver), and steel wool to remove burrs.
- Primer pocket uniformer tool (battery screwdriver)
- Inside Nylon case brush to ensure insides have nothing stuck within (Use battery screwdriver)

For any of the calibres/cartridges that I need to FL size each time, I pretty much just follow process a)..

At this point, the cases are ready to load.
- Prime with an RCBS hand-primer
- Powder dispensed with RCBS Chargemaster
- Measure COAL with calipers
- Weigh loaded cartridges, and record weight variation in batch.
- Write up reloading log & sticker for ammo box.

At some stage before Christmas, I'll set up a home-made annealer, and at that stage, I might change the processes a bit.

This is my regime, and it works for me. I'm not asking anyone else to adopt it.
To other reloaders, It's probably overly complicated in some areas, and too simplistic in others.
But it works for me.
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