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 Less headspace on a once fired round..How?
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ruthless4645
Starting Member

9 Posts

Posted - Oct 28 2016 :  10:48:13  Show Profile Send ruthless4645 a Private Message  Reply with Quote
Need a little advice, I'm shooting a .270WSM, currently using Federal Vital Shok (accubonds). The headspace length on an UNFIRED cartridge measures 1.770" using my Hornady headspace guage (insert #375).

However, on the SAME case after I've FIRED it I consistently get a measurement of 1.768"........How is that possible?, how did I lose headspace lenght, I always thought the case became larger through fire forming not smaller.

**I tested this on 20 fired rounds with the same results..

Edited by - ruthless4645 on Oct 28 2016 11:02:19

Kosh75287
Advanced Member



USA
796 Posts

Posted - Oct 28 2016 :  11:40:35  Show Profile Send Kosh75287 a Private Message  Reply with Quote
If the brass expands to fill the chamber by expanding against the chamber's sides, I would expect brass to flow from the thinnest part(s) of the case (the neck & shoulder), decreasing their dimensions. Have you resized any of those cases? It's been my experience that cases tend to get longer during the resizing operation, not when being shot.

God bless Jeff Cooper

Carpe SCOTCH!
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Shastaboat
Advanced Member



USA
9124 Posts

Posted - Oct 28 2016 :  11:53:11  Show Profile Send Shastaboat a Private Message  Reply with Quote
That is normal. The difference is .002. It has to do with the brass flowing from the shoulder into the neck. I'm not a physicist and can't really explain how or why it happens but it does to some degree in all bottleneck cartridges. I'm not sure how hot or mild you are loading but I suspect you might be loading a bit light. Is your primer backing out any?

Edited by - Shastaboat on Oct 28 2016 11:55:16
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ruthless4645
Starting Member

9 Posts

Posted - Oct 28 2016 :  12:45:14  Show Profile Send ruthless4645 a Private Message  Reply with Quote
quote:
Originally posted by Kosh75287

If the brass expands to fill the chamber by expanding against the chamber's sides, I would expect brass to flow from the thinnest part(s) of the case (the neck & shoulder), decreasing their dimensions. Have you resized any of those cases? It's been my experience that cases tend to get longer during the resizing operation, not when being shot.



Thank you very much for the fast response. The BODY diameter of the case did blow out a little bit and became larger (it would not fit within the parameters of my Wilson case length gauge. So I used a Redding Body (only) die along with a Redding precision shell holder (+10) to stop the die from moving the shoulder, the headspace length remained the same. Now the case will fit nicely into the Wilson gauge, however I'm still exactly .002 short on my headspace length.

Not overly worried, more curious. I reload for many other calibres and have never experienced this!. Headspace (OAL length to shoulder datum line) usually grows slightly after firing, I've never seen it shrink!. To more accurately answer you.

After using the "body only die" (with a +10 shell holder).

1. The case now fits very nicely now in the Wilson gauge.
2. Headspace never moved...Still short .002"
3. I never had to trim the case lenght, it's perfect.

Edited by - ruthless4645 on Oct 28 2016 15:12:15
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ruthless4645
Starting Member

9 Posts

Posted - Oct 28 2016 :  13:03:18  Show Profile Send ruthless4645 a Private Message  Reply with Quote
quote:
Originally posted by Shastaboat

That is normal. The difference is .002. It has to do with the brass flowing from the shoulder into the neck. I'm not a physicist and can't really explain how or why it happens but it does to some degree in all bottleneck cartridges. I'm not sure how hot or mild you are loading but I suspect you might be loading a bit light. Is your primer backing out any?



I HAVEN'T reloaded any of these cartridges yet. This is a comparison between BRAND NEW unfired Federal rounds and the same "ONCE fired" (but not yet reloaded) cases. Trying to figure out how I LOST .002 by firing this factory ammo only once..

Edited by - ruthless4645 on Oct 28 2016 13:05:03
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F. Guffey
Advanced Member

USA
961 Posts

Posted - Oct 28 2016 :  14:16:25  Show Profile  Visit F. Guffey's Homepage Send F. Guffey a Private Message  Reply with Quote
quote:
Need a little advice,



ruthless4645, you ask for a little advise; in my opinion that is all you got, a little, very little.

First, your case does not have head space and the tool your are using is not a head space tool. I know, reloaders believe everything has head space and all tools are head space tools.

F. Guffey


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ruthless4645
Starting Member

9 Posts

Posted - Oct 28 2016 :  14:32:53  Show Profile Send ruthless4645 a Private Message  Reply with Quote
quote:
Originally posted by F. Guffey

quote:
Need a little advice,



ruthless4645, you ask for a little advise; in my opinion that is all you got, a little, very little.

First, your case does not have head space and the tool your are using is not a head space tool. I know, reloaders believe everything has head space and all tools are head space tools.

F. Guffey

Soooooo, you slam on me for not understanding, and others for trying to help me out...Yet you offer nothing?

Go away and stop bothering me and the others please. You sound like a very pompous ass with far too much "Head Space"..


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WonderMan4
Advanced Member

USA
2849 Posts

Posted - Oct 28 2016 :  15:52:39  Show Profile Send WonderMan4 a Private Message  Reply with Quote
Well, for another one, I happen to agree with Mr. Guffey in that only a chamber has headspace.

You say he offered nothing, well, I beg your pardon, he offered you the correct terminology.

The measurement that you are referring to is called Cartridge Base to datum. It is not headspace. Headspace is measured from the bolt face.

I think it is typical for a cartridge to expand when fired and then shrink when the brass relaxes. If you use a comparator, you can see the difference on each cartridge that you fire in any caliber.

YOu may not like his style, but he is a wealth of knowledge. And here you are trying to piss him off right at the start.
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Leatherstocking
Average Member

Canada
144 Posts

Posted - Oct 28 2016 :  18:53:53  Show Profile Send Leatherstocking a Private Message  Reply with Quote
Thanks Wonderman. Have to agree that Mr. Guffey is a wealth of knowledge,which he shares regularly on this forum. He is pedantic, and his writing style is cryptic, but further investigation proves the worth of his tidbits.
In Ruthless' defence, Hornady sells a "headspace gage" which measures not headspace, but cartridge length to datum. So the terminology is confused even by Hornady.
In some cases headspace is not measured to the datum on the shoulder of the chamber as rimless chambers are. 45 acp is measured from bolt face to the neck, where the brass is stopped. Belted magnums from bolt face to where the belt hits the chamber, and rimmed cartridges from bolt face to where the rim contacts the chamber.
Headspace is the concern of those reaming chambers.
What we are usually concerned about in reloading is shoulder clearance, as we can custom form the brass to fit our particular chamber. I mean the clearance between the chamber shoulder and the shoulder of the case.
If this clearance is not sufficient, the round will not chamber. If too large, the brass is over worked at least, and case head separation is also an option.
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ruthless4645
Starting Member

9 Posts

Posted - Oct 28 2016 :  19:53:06  Show Profile Send ruthless4645 a Private Message  Reply with Quote
quote:
Originally posted by WonderMan4

Well, for another one, I happen to agree with Mr. Guffey in that only a chamber has headspace.

You say he offered nothing, well, I beg your pardon, he offered you the correct terminology.

The measurement that you are referring to is called Cartridge Base to datum. It is not headspace. Headspace is measured from the bolt face.

I think it is typical for a cartridge to expand when fired and then shrink when the brass relaxes. If you use a comparator, you can see the difference on each cartridge that you fire in any caliber.

YOu may not like his style, but he is a wealth of knowledge. And here you are trying to piss him off right at the start.



Piss him off?....Neither he, nor you, have offered me ANY HELP or knowledge concerning this problem, other than condescending remarks. Then he insults other posters that were trying to help me.. What a tiny and small poster he is. BTW, the tool is called the "Hornady headspace Gauge". But I most humbly and sincerely apologize, and will throw myself down on my sword if I have insulted your Gurus' VAST knowledge of reloading and it's terminology....I'm NEW to this...Which is why I was asking for HELP!

What does one need to do?, beg an audience with this "Idiot Savant Guru" only then to be put to his lash because of their lack of knowledge and terminology?

Other than explaining NOTHING to me about why I'm seeing this particular problem only in my .270WSM and not in any of the other cartridges I reload for, all you've done is defend this VERY poor excuse of a teacher of reloading knowledge.....So in my book you're both equal.....POOR.

I was told/warned about this site on several other websites I'm on, but I took a chance anyway in the hope that I might glean some good and friendly shooting community advice for this problem I'm having. Apparently I was very mistaken.....Sorry I asked for help, no harm no foul.

Man, what a broken and disturbing forum this is. No need to reply, you'll just be killing a ton of pixels and your fingers tips.

Hey just a heads up, If you want to mentor new reloaders' (which is what I thought this is suppose to be all about) learn how to teach!. You've now gained one more person to spread the word about this place, and not in a good way!

Edited by - ruthless4645 on Oct 28 2016 20:31:02
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K22
Senior Member

442 Posts

Posted - Oct 28 2016 :  20:41:59  Show Profile Send K22 a Private Message  Reply with Quote
Let me say first off I have no experience with reloading short magnum calibers.

But in my experience the best way to control cartridge head spacing is to full length resize the case with a .001 to .002" shoulder bump for bolt rifles. This will accomplish a number of positive things: 1. will prevent over sizing the case which can lead to excessive head spacing, 2. will provide uniform sizing which will contribute to accuracy, 3. will provide improved functionality (i.e. ease of chambering and extraction.)

If you have a Hornday Headspace tool then you have the correct tool to adjust your die to measure the amount of shoulder set back. The set back you want to measure is that from a fired case in the specific rifle that you are loading for.
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ruthless4645
Starting Member

9 Posts

Posted - Oct 28 2016 :  21:12:45  Show Profile Send ruthless4645 a Private Message  Reply with Quote
quote:
Originally posted by K22

Let me say first off I have no experience with reloading short magnum calibers.

But in my experience the best way to control cartridge head spacing is to full length resize the case with a .001 to .002" shoulder bump for bolt rifles. This will accomplish a number of positive things: 1. will prevent over sizing the case which can lead to excessive head spacing, 2. will provide uniform sizing which will contribute to accuracy, 3. will provide improved functionality (i.e. ease of chambering and extraction.)
If you have a Hornday Headspace tool then you have the correct tool to adjust your die to measure the amount of shoulder set back. The set back you want to measure is that from a fired case in the specific rifle that you are loading for.



Thanks K22.

The problem I'm having is my "Once fired cases" are actually .002" shorter from the case head to the shoulder datum line than the original factory case they were fired from, BEFORE, I even touch them. I'm trying to figure out why that is occurring (new to this stuff). Every other caliber I own has always increased a little in length after fire forming, not decreased. Not a big deal just a curiosity, but thanks for the reply.
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Shastaboat
Advanced Member



USA
9124 Posts

Posted - Oct 28 2016 :  21:44:31  Show Profile Send Shastaboat a Private Message  Reply with Quote
ruthless4645, you have fallen victim of trying to make handloading way to complicated. I've been hand loading for over 50 years and I have never had the need to use a "headspace gauge", "case length gauge" or a specific Redding Sizing die "Body" only or a Redding "Precision" shell holder. I have used various sizing die bodies less the expander to form cases from a parent case. What do you think you are going to accomplish? As for the measurement of .002", find a feeler gauge and see how thin we are talking. If you want to measure something just for the heck of it, measure "with a micrometer" the case web size before firing and then after firing. You will find that the difference tells you how wide the diameter of your chamber is. Then set up your full length sizing die and see if it sizes back to the factory dimension. If not, it is no big deal because your chamber is always going to be larger than your loaded ammo. I tried to explain to you that firing a round will do exactly what you described. When you size your case you may find it actually pushes the shoulder forward that .002". You haven't discovered anything that others have not seen in the past. I sUspect that when the case expands in the body to fill the chamber it pulls the shoulder back that .002". But since that is what always seems to happen, what difference does it make. Do yourself a favor and "loose" that headspace gauge, buy a digital or dial caliper, and follow your die directions in setting up your loading dies. Start shooting and when you can consistently shoot .500" groups at 100 yards then you really won't have the need to ask a question about .002" of perceived headspace. KISS=KEEP IT SIMPLE STUPID.

Edited by - Shastaboat on Oct 28 2016 21:45:52
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ethmoid1999
Advanced Member



USA
4398 Posts

Posted - Oct 28 2016 :  22:22:53  Show Profile Send ethmoid1999 a Private Message  Reply with Quote
+1 Shasta.
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woods
Advanced Member

USA
2132 Posts

Posted - Oct 28 2016 :  23:04:07  Show Profile Send woods a Private Message  Reply with Quote
Really an unusual result. I reload for over 40 different rifles and, like you said, the shoulder moves forward during firing. Usually until you get a crush fit and have to move the shoulder back slightly to facilitate chambering.

It could be that you are pushing the shoulder back when you actually chamber a round. IOW your chamber dimension from case head to shoulder datum is 1.768" and by chambering you are sizing. Just a thought.

And you are right about having to cut through a lot of BS to separate wheat from chaff around here sometimes. Falls into the category of "It takes all kinds of people to fill the freeway". Example Shasta believes in simplistic reloading and I am the exact opposite. Learn all you can, that's what makes it interesting. Guffey obviously knows a lot but has a real problem conveying that information in a cogent manner. I usually agree with Wonderman, not this time.

Personally I hope you pick your lane and set your speed on this freeway rather than take the exit


When someone shares something of value with you and you benefit from it, you have a moral obligation to share it with others.

After Tuesday, even the calendar says WTF!

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WonderMan4
Advanced Member

USA
2849 Posts

Posted - Oct 28 2016 :  23:57:32  Show Profile Send WonderMan4 a Private Message  Reply with Quote
quote:
It could be that you are pushing the shoulder back when you actually chamber a round.


The 270 WSM has a large shoulder. It would take quite an effort to size the case by closing the bolt....even as little as 0.002".

I have seen just the opposite effect with the 300 WSM. It will not re-chamber after firing andwill not chamber after neck sizing.

quote:
I usually agree with Wonderman, not this time.


I usually agree with woods as he is another wealth of knowledge, but I don't agree with him this time.

Shasta might be on the path if you are loading light.

Usually though if the load is light, the case will get soot on it from not sealing the chamber well enough when fired.

Edited by - WonderMan4 on Oct 29 2016 00:01:57
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