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Old May 18, 2015, 08:11 PM   #51
sirgilligan
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And one last one, which again distinguishes cartridge headspace.

http://www.sinclairintl.com/.aspx/li...th-Sizing-Die-

"Cartridge Headspace and Over Sizing
Cartridge headspace can be defined as “how much the cartridge case moves forward and backward in the chamber upon firing when the breech or action is fully closed”. When a chamber is reamed by a manufacturer or gunsmith, there are maximum and minimum dimensions that SAAMI (Sporting Arms and Ammunition Manufacturer’s Institute) specifies for the chamber for a particular cartridge. This dimension determines the fixed headspace of the rifle’s chamber.... Excessive sizing will also allow your brass to chamber easily but will create excessive headspace. This extra headspace will allow the case to have excessive forward and backward movement when it is fired....
"
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Old May 18, 2015, 08:18 PM   #52
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Those reloading book quotes are saying the same thing in different ways. The Speer quote is merely telling you to not set the shoulder back too far when you resize it. If you do, the case (when fired) will stretch more than you want it to. You will have put a case that is shorter (from base to shoulder) than desired. When fired it will stretch to fill the chamber, and work the brass more than would be desired. That will lead to case head separations eventually. I know this from experience. The Hornady quote is saying the same thing in a different way. The case with the shoulder set too far back will move forward with the firing pin strike, the powder will ignite and the case will stretch and fill the chamber. So don't set the shoulder too far back. Adjust your sizing die to set the shoulder back just enough that the round will chamber without noticeable resistance.

That's about the best I can do to respond to your question.

Where's BartB? He loves stuff like this.
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Old May 18, 2015, 08:21 PM   #53
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Larry Willes is wrong . Not only that but technically there is no such thing as case/cartridge head space . Now most if not all hand loaders use the term anyways excluding Mr Guffey . If you look at the SAAMI specs the is no term for the length of the cartridge from head to datum point
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Old May 18, 2015, 08:27 PM   #54
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Quote:
Those reloading book quotes are saying the same thing in different ways. The Speer quote is merely telling you to not set the shoulder back too far when you resize it. If you do, the case (when fired) will stretch more than you want it to. You will have put a case that is shorter (from base to shoulder) than desired. When fired it will stretch to fill the chamber, and work the brass more than would be desired. That will lead to case head separations eventually. I know this from experience. The Hornady quote is saying the same thing in a different way. The case with the shoulder set too far back will move forward with the firing pin strike, the powder will ignite and the case will stretch and fill the chamber. So don't set the shoulder too far back. Adjust your sizing die to set the shoulder back just enough that the round will chamber without noticeable resistance.

That's about the best I can do to respond to your question.
Thanks.

I get what it is talking about, I am just pointing out that they call it head space.

What I have learned from this is that there are two types of headspace, if you will.

The headspace that is set when the chamber is fixed to the action and is measured from the closed bolt face to the point inside the chamber. This headspace is fixed / constant so to speak.

Cartridge headspace is how well the cartridge fills the chamber headspace. Setting the shoulder back too far creates cartridge headspace which is indicated by the space between the bolt face and the head of the cartridge when the cartridge is as forward as it can go.
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Old May 18, 2015, 08:28 PM   #55
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Larry Willes is wrong . Not only that but technically there is no such thing as case/cartridge head space . Now most if not all hand loaders use the term anyways excluding Mr Guffey . If you look at the SAAMI specs the is no term for the length of the cartridge from head to datum point
Is the Hornady and Speer manuals wrong as well? They clearly state that headspace can be created.
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Old May 18, 2015, 09:09 PM   #56
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They say head space can be created . They don't say that space is the head space measurement . If a case is sized really short you can have excessive head space as well . The thing about all this is you MUST understand what the actual definition of head space is . You then can incorporate the term in other areas of reloading and most will understand what you're talking about . I know it sounds complicated but as long as you except there is only one true head space measurement the rest will fall into place .

Let's ask this , how do you check head space ? And what are you measuring . Do you use a sized cartridge or a gage that is set at a industry standard measurement .

How about this ? Let's say you have a chamber that head spaces .020 larger then the SAAMI maximum . You then size a case that fits tight in the chamber . Does the chamber have excess head space ? Interesting right
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Old May 18, 2015, 09:19 PM   #57
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Wow! I thought I explained that, sirgilligan. Go to post number 2 by Unclenick and read and reread the first sentence. Read it till it makes sense.

Yes, you can 'create' headspace. If you oversize the case, or in other words if you set the shoulder too far back. You have created headspace. If you set the shoulder back like Goldilock's porridge, it'll be just set back enough and not too much, and will be just right.

As for how much to set the shoulder back, it will depend on your rifle's chamber. Some are roomy and some are snug. For my 220 I have to resize the case as much as the press, die, and shellholder will allow. The chamber in the Douglas barrel is very snug. For a Ruger I once had, the chamber was rather roomy and I didn't want to resize the case more than necessary, which would have created excess headspace, so I'd lightly set the shoulder back on the case which had been fireformed to my chamber.
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Old May 18, 2015, 09:43 PM   #58
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So back to the original post:

Quote:
Loaders:
I think I don't understand what "Head space" is.
Help.
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How does anyone know which head space he is referring to?

Is it the chamber head space, or the head space that is created by making a case too short?

These are rhetorical questions, but maybe the OP would care to answer.
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Old May 18, 2015, 10:22 PM   #59
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It does not get any more official then this . Notice that the sporting arms and ammunition manufacturers institute (SAAMI) only has one definition for head space .

http://saami.org/glossary/display.cfm?letter=H
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Old May 18, 2015, 10:45 PM   #60
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Well, there are too many books and online sources that perpetuate the definition that I submitted. I may be wrong, but I have lots of company.

http://www.gundigest.com/headspace-1...rifles-chamber

"Altering case dimensions changes the relationship of the cartridge to the chamber. Reducing head-to-datum line length of the round can result in a condition of excess headspace, even if the firearm checks out perfectly."



http://www.redding-reloading.com/tec...with-headspace

"Headspace is one of those concepts that is both very simple and yet is extremely important to achieve gilt edged accuracy. For bottlenecked cartridges, headspace is simply the distance between the head of the cartridge case (the end where the primer is inserted) and the front/face of the firearm's bolt when the case's shoulder is positioned against the front of the chamber.... Headspace is like Goldilocks porridge. It has to be just right for the best accuracy. Too much is bad and too little is also bad. "

From the Forster Products Headspace Gage Instructions:
"Headspace is the distance between the face of the breech and the base of the cartridge when the action is closed."
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Old May 19, 2015, 05:47 AM   #61
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Quote:
It does not get any more official then this . Notice that the sporting arms and ammunition manufacturers institute (SAAMI) only has one definition for head space .
In other words, when we blow out a case to fit the chamber, we are now shooting non-SAAMI ammo. The rifle still has too much head space for SAMMI spec ammo but the custom out of SAMMI spec ammo we load for it fits perfectly.
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Old May 19, 2015, 06:23 AM   #62
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HeadSpace Dimension is HeadSpace Dimension... be it chamber or case; be it base-to-shoulder datum diameter, base-to-mouth, or base-to-rim- front(thickness).

When...
- HSDchamber = Headspacecase, you have no HeadSpace Clearance
- HSDchamber less than Headspacecase, you have negative HeadSpace Clearance (jammed case)
- HSDchamber greater than Headspacecase, you have positive HeadSpace Clearance (rattle room)
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Old May 19, 2015, 06:26 AM   #63
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Headspace threads are the best
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Old May 19, 2015, 08:08 AM   #64
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Overthere, over here I use the length of the case from the shoulder to the head of the case to off set the length of the chamber from the shoulder of the chamber to the bolt face.

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Old May 19, 2015, 08:14 AM   #65
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Quote:
Cartridge headspace can be defined as “how much the cartridge case moves forward and backward in the chamber upon firing when the breech or action is fully closed”.
Quote:
headspace is simply the distance between the head of the cartridge case (the end where the primer is inserted) and the front/face of the firearm's bolt when the case's shoulder is positioned against the front of the chamber.
Quote:
"For every complex problem there is an answer that is clear, simple, and wrong." H. L. Menken
Neither of the two quoted definitions of headspace is correct. They define what is called head clearance (see SAAMI glossary). Head clearance is the amount by which chamber length is greater than the cartridge requires to fit into it.

Head Clearance = Headspace – Space Occupied by Cartridge Case

When you over-resize a case, you shorten the portion of the headspace occupied by the cartridge, thereby increasing the head clearance. But the headspace is cut into the chamber, so it remains the same.

In the SAAMI system, measurement of the case seat location is defined by the headspace datum. In the CIP and NATO systems, it is defined by the location of the shoulder and body intersect for rimless bottleneck cartridges, same as we did it here until SAAMI came up with the datum approach (sometime after WWII, I infer, from the way the dimensions are defined in publications). The advantage of the datum method is the datum has the same size and location on both chambers and their cartridge cases. However, that is also what has lead to the confusion.

The space in the chamber that is occupied by the cartridge case in the above equation has commonly come to be called "case headspace" or "cartridge headspace" but they are not in SAAMI's glossary as proper terms. I am convinced they came about because of the RCBS Precision Mic, and Stoney Point case comparators. These tools measure a fireformed rimless bottleneck rifle case as an indirect or transfer measurement of the chamber's headspace, and their instructions correctly call that a headspace measurement, even though it's not direct nor as precise as a direct measurement (owing to brass springback). But people seemed to get confused by being asked to measure a case to find headspace, and pretty soon many started to think any case measurement from head to datum, fireformed or not, was the headspace. They were wrong. But the misapplied term has stuck in one way or another, as the two faulty definitions I quoted at the start of this post illustrate. The only thing I know to do until a better term comes along and since the misuse won't seem to come out of the vernacular, is to be careful to modify it by putting the word "case" or "cartridge" ahead of it as mentioned at the start of this paragraph.

In past posts I've called for creation of a term for this. The obvious candidate is headsize. It parallels headspace, but has the same intrinsic confusion caused by the fact the head isn't the only thing included, except in rimfire cases. Casespace is another candidate, but still can be confused as meaning headspace. Suggestions would be welcome if someone has a better idea.
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Old May 19, 2015, 08:42 AM   #66
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Quote:
The only thing I know to do until a better term comes along and since the misuse won't seem to come out of the vernacular, is to be careful to modify it by putting the word "case" or "cartridge" ahead of it as mentioned at the start of this paragraph.
I make every attempt to avoid the term 'head space'. To some everything has head space and every gage is a head space gage. Motive: google search and the nature of a forum. Forums have a tendency to polarize. They just can not help it 'Go Jimmy'.

If the tool is a comparator, call it a comparator, if it is a case gage, call it a case gage. A reloader with little to no ambition can call a Wilson Case gage a drop-in gage, a reloader with shop skills can use the Wilson case gage for what it is, a very precision datum based tool.

Then there is that old saying, it goes something like speaking where the book speaks and being silent where the book is silent.

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Old May 19, 2015, 08:44 AM   #67
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Well, optimistically I think we are all doomed.

When I read my reloading manuals, which we are all supposed to do, and both use the same description, and then when I read the manuals for reloading dies and headspace gauges and they use the same description, and then I read the online "tips from pros" on the reloading company's websites that use the same description I think the damage is done.

Therefore the discussion, which is true for most discussions, comes down to semantics.

Therefore, if someone asks a question about headspace, context is everything.

Are you re-barrelling your rifle and want to know how to set it so that an in-spec cartridge will go in and allow the bolt to close?

Do you have a new rifle and the bolt will not close on any factory load and you want to know what to measure to see what is wrong or out of spec?

Are you reloading and your cartridges seem to be too long because the bolt will not close, but you measured the overall all length and the cartridge is not too long?

Are you reloading and your cartridges go in fine, but the case head is getting thin only after a few reloads or you are seeing actual case head separation?
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Old May 19, 2015, 08:51 AM   #68
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Unclenick, I've got this solved.

The term that should be used for this measurement is 'Casefit'.

As in, 'for optimum accuracy you should make sure your Casefit is two thousands shorter than the Headspace'

And with the implied nouns added:

'for optimum accuracy you should make sure the Casefit of your case is two thousands shorter than the Headspace of your chamber'

There, world peace
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Old May 19, 2015, 09:01 AM   #69
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Doomed I say, doooomed.

Okay, I will do some quick, of the top of my head, brain storming... anything goes...

Cap Gap
Case Spase
Brass ... well you know what rhymes with it
Slop stop


When the chamber is the topic and the thing that is being investigated and/or adjusted then the term chamber could be used.

When the cartridge is the topic and the thing that is being investigated and/or adjusted then the term cartridge could be use.

I don't know, I am too new at all of this, and besides, as a programmer, I get sick of coming up with variable names.
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Old May 19, 2015, 09:14 AM   #70
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There has been many times in history when enough people have referred to something wrongly enough times the new term had become an exceptable definition . That is what happen here . It does not make it correct , It's just excepted . As Unclenick said : the head space is cut into the chamber . Head clearance is the open space around a cartridge when it's chambered . Case/cartridge head space is a measurement taken from somewhere on the case . They are not all head space people just call them all head space
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Old May 19, 2015, 10:52 AM   #71
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You can see why I am . . . confused.

Sirgillian:

In response to your earlier post about which "headspace" I am asking about . . . I don't know. From the plethora of answers I've received to my OP I can see that this term is used in several ways and as an earlier post noted "context" is everything. And the host of posts above make it clear why a neophyte like myself might experience some ambiguity about "headspace."

So, "chamber" is the space where the ammunition resides when it is lined up with the barrel, the bolt is closed, and it is ready to be fired. "Headspace" is the size of the chamber in relation to the size of the cartridge. If the cartridge is too big then there is not enough "headspace" and if the cartridge is too small then there is too much "headspace." And the point is that all of these dimensions and how the cartridge fits in the chamber has a real effect on what happens to the bullet when the trigger is pulled. Is that the general idea?
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Old May 19, 2015, 12:29 PM   #72
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Prof Young,

To me it sounds like you are on the right track.

I might rephrase your statement to say if the cartridge is too long or too short along a particular line instead of too big or too small. The only reason is that a case could be too big around / too fat and not fit into the chamber.
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Old May 19, 2015, 12:40 PM   #73
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Quote:
The only reason is that a case could be too big around / too fat
hmm , you know since we are excepting other definitions for head space . Lets make up some more .

The open space around the body of a case when chambered will be called BODY head space

The open space between the the case shoulder and chamber shoulder when chambered but only if the head is up against the bolt face will be called SHOULDER head space

The space between the case mouth and forward most chamber ridge when chambered will be called CASE MOUTH head space

There I think that should cover all the head spaces
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Old May 19, 2015, 10:39 PM   #74
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Those that talk about head space have to purchase head space gages. It reminds me of being politically correct. Harry Truman lectured someone on being politically incorrect.

People make gages, for the longest I thought smiths and reloaders believed head space gages ware made on Mars by Martians.

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Old May 19, 2015, 11:27 PM   #75
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Quote:
reloaders believed head space gages ware made on Mars by Martians.
What does a head space gage measure or gage ?

Is it the space between the bolt face and the head of a chambered cartridge ?

Does a head space gage , gage if you sized your case to small ?

There must be something they were designed to measure ??? If we only knew what that was maybe we could settle this . oh well I guess we will never know what those things are for
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