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Old April 5, 2012, 06:31 PM   #26
dmazur
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See, I fell into using inexact terminology...

I had already explained how I believed "headspace" is misused.

What I meant was that if you had reasonable (that is, small) head clearance, you probably had proper headspace. And then went on to explain how a bolt action might handle less head clearance than a semi-auto.

If you just assume the term "headspace" means anything in particular, out of context, you often miss the intent.
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Old April 5, 2012, 07:50 PM   #27
Bart B.
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dmazur comments:
Quote:
What I meant was that if you had reasonable (that is, small) head clearance, you probably had proper headspace. And then went on to explain how a bolt action might handle less head clearance than a semi-auto.
Well put. Small head clearance is very desirable.

That said, when 30 caliber service rifles were the norm in high power service rifle matches, the military team riflesmiths rebuilt them with the same head clearance as bolt guns; 2 to 3 thousandths inch. Barrels used were typically pre-chambered to finished dimensions so they had to go through a bucket of bolts until one that just barely closed on the GO headspace gage (minimum chamber headspace spec). As both service and civilian new match ammo in both .30-06 and 7.62 NATO had average case headspace about 2 to 3 thousandths less, the best of those semiauto M1 and M14 rifles shot almost as accurate as bolt action rifles. And they functioned flawlessly.

Nowadays, with the M16 and its semiauto variants shooting the 5.56 NATO or .223 Remington round, they're headspaced the same way; small head clearance.
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Old April 5, 2012, 07:50 PM   #28
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Forget "headspace", it's a measure of the chamber - only - and is virtually irrelivant to a competent reloader. Thus, how it's measured and set by the manufactor is meaningless to us.. we live with what ever chamber we have.

Ignore all the technical explainations and think of headspace as the firearm's space for the cartridge; if the space is too small we can't chamber a round, if it's too large the cases will have to expand too much each time it's fired and that leads to excessive case stretching and will - eventually - result in a head seperation, which ain't good!

Reloaders only need to know where the shoulders of the fired bottle neck cartridges are and adjust their FL dies to restore that measurement during sizing. It matters not if the case is rimmed, rimless or belted, we just resize so the shoulder is at the same place or a tad less than the fired location and that's perfection. (It's NOT necessary to set the shoulders back an additional few thou, the fired cases have already shrunk back a thou or so from the chamber size.)

You can adjust cases to custom fit a chamber by carefully running the sizer down while doing test fits in the rig but it's harder to do correctly than it may appear. Most of us use a case shoulder gage such as the Hornady, Sinclair or RCBS Precision Case Mic. All reloaders need a 6" caliper anyway so getting one of the moderately priced Hornady "headspace" kits to use on a caliper is the most flexible and cost effective way to go and you can set your sizers very precisely with that combonation.

There is no way to 'adjust' anything but the case length itself in straight walled cases but few of them ever grow too long anyway. If they do get too long we use a case trimmer to fix 'em.
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Old April 5, 2012, 08:35 PM   #29
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wncchester exclaims:
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Forget "headspace", it's a measure of the chamber - only - and is virtually irrelivant to a competent reloader.
True. Except most of us were helping someone new to reloading and the language, terms, tools, and measurements learn about headspace; something you are already competent in. So give both us and him a break......thanks.
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Old April 6, 2012, 07:48 AM   #30
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dmazur comments:
Quote:
What I meant was that if you had reasonable (that is, small) head clearance, you probably had proper headspace. And then went on to explain how a bolt action might handle less head clearance than a semi-auto.

Well put. Small head clearance is very desirable.

That said, when 30 caliber service rifles were the norm in high power service rifle matches, the military team riflesmiths rebuilt them with the same head clearance as bolt guns; 2 to 3 thousandths inch. Barrels used were typically pre-chambered to finished dimensions so they had to go through a bucket of bolts until one that just barely closed on the GO headspace gage (minimum chamber headspace spec). As both service and civilian new match ammo in both .30-06 and 7.62 NATO had average case headspace about 2 to 3 thousandths less, the best of those semiauto M1 and M14 rifles shot almost as accurate as bolt action rifles. And they functioned flawlessly.

Nowadays, with the M16 and its semiauto variants shooting the 5.56 NATO or .223 Remington round, they're headspaced the same way; small head clearance.




If they went through a bucket of bolts to change head space they would still be looking, THEY WERE GUN SMITHS! THEY HAD REAMERS! They had modified bolts (modified bolts?). I have no less than 30 03/03A3 replacement bolts, there is not .001 + or - thousandths difference between all of them, a builder, collector resource type person has no less than 60+, again, good luck changing bolts to change head space, BUT! if you decide to change head space on your Springfield and can take instructions I can save you a trip and time, I have heard that all my life “order extra bolts just in case the head space is not correct”.

The rifle barrel had to be indexed, lines had to be aligned, seems there was an extractor cut, again, they had modified bolts, wait! I forgot, I have modified bolts, I hauled those bolts through 3 different gun shows, no one had a clue what they were, finally, the collector, builder resource type person called and said you are correct etc., etc., seems he went back through his library and found they used tools we, today, do not know existed.

dmazur comments:
Quote:
If you have true excess headspace, you can't fix it by adjusting the resizing die. You have to make the headspace shorter in the rifle, by installing a new barrel or possibly a longer bolt (if available in sizes.) The die isn't the solution.

That's true, usually. The one exception I came across was a Win. 70 that had a used factory .30-06 barrel installed to replace the original factory .270 Win barrel. And some folks end up with "true excess headspace" for one of several reasons.


dmazur comments:
Quote:
What I meant was that if you had reasonable (that is, small) head clearance, you probably had proper headspace. And then went on to explain how a bolt action might handle less head clearance than a semi-auto.

Well put. Small head clearance is very desirable.

That said, when 30 caliber service rifles were the norm in high power service rifle matches, the military team riflesmiths rebuilt them with the same head clearance as bolt guns; 2 to 3 thousandths inch. Barrels used were typically pre-chambered to finished dimensions so they had to go through a bucket of bolts until one that just barely closed on the GO headspace gage (minimum chamber headspace spec). As both service and civilian new match ammo in both .30-06 and 7.62 NATO had average case headspace about 2 to 3 thousandths less, the best of those semiauto M1 and M14 rifles shot almost as accurate as bolt action rifles. And they functioned flawlessly.

Nowadays, with the M16 and its semiauto variants shooting the 5.56 NATO or .223 Remington round, they're headspaced the same way; small head clearance.




My press and dies have threads, threads make my die adjustable in the press, the amount of sizing as in reducing the length of the case from the head of the case to the shoulder of the case is fixed (for most) as in full length sizing to minimum length, I have an additional –.012 thousandths available for short chambers. Minimum length, nothing written says I must size to minimum length, my chambers are not adjustable, the length of the chamber is fixed, my press and dies have threads so omit or exclude ‘me’ from “
If you have true excess headspace, you can't fix it by adjusting the resizing die. You have to make the headspace shorter in the rifle, by installing a new barrel or possibly a longer bolt (if available in sizes.) The die isn't the solution.


because I can adjust my die off the shell holder, I prefer the standard, transfer, validator, the feeler gage, again there is full length sizing to minimum length, beyond that? there is infinity or a more practical .014 thousandths beyond minimum length when sizing cases for my M1917 Eddystone (not uncommon). Then there is the “where is the head space?”, we will never get around to discussing that one because of political correctness.

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Last edited by F. Guffey; April 6, 2012 at 07:52 AM. Reason: add ?
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Old April 6, 2012, 08:31 AM   #31
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"True. Except most of us were helping someone new to reloading and the language, terms, tools, and measurements learn about headspace; something you are already competent in. So give both us and him a break......thanks."

You're welcome and, yes, I am. And by giving him - and "us" - relivant info, correct terms plus practical and proper means of measurements for what he's seeking to accomplish would seem to be giving everyone a break, or is it not ??
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Old April 6, 2012, 12:08 PM   #32
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John,

The head of a case is what is called the pressure bulkhead in a pressure vessel (the end pressure barrier). The term "head" is just a shorter form of that, though I don't know the actual order of evolution of the terms. The meaning is the same, though.

Hatcher has a good description of the term "headspace". He points out that when the term was coined in the early days of cartridge firearms, the rim was all that stopped pressurized gas from escaping between the end of the chamber and the breech face (i.e., in rimfire cartridges), so the distance from the breech face to the part of the chamber end the rim stopped against was all the wiggle room or space the gun had for the head, and that's where the term headspace comes from. Later, when rimless cases were developed that were designed to have their cases stop against a case mouth, shoulder, or belt, the term was simply carried over to whatever measure of the longitudinal distance from the breech face to the stopping surface was used, even though it no longer had its literal meaning of "space for the head" in those instances.

Confusion occurs when people speak of measuring headspace on a cartridge case. This is an issue only with bottleneck rimless cases without belts. It's a measurement done from the head to a specified diameter on the shoulder called a headspace datum that is the same diameter in the chamber and on the case so they are coincident when a case fills a chamber completely. That means that on the case it doesn't actually reflect headspace unless the case has first been fireformed to fill all the available headspace up. If you do fireform a case and measure it, you then can compare it to sized cases to see how much wiggle room there will be for them in the chamber. As explained above, you don't want too much for best precision (smallest group size) and best case life.

SAAMI has a glossary of terms you may find useful.
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Last edited by Unclenick; April 7, 2012 at 02:22 PM. Reason: clarification
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Old April 6, 2012, 12:17 PM   #33
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Quote:
Later, when rimless cases were developed that were designed to have their cases stop against a case mouth, shoulder, or belt, the term was simply carried over to whatever measure of the longitudinal distance from the breech face to the stopping surface was used, even though it no longer had its literal meaning of "space for the head" in those instances.
Unclenick,

How does this work for semi-rimmed cartridges like the .220 Swift. Just curious, as I had an earlier thread about headspacing and sizing my Swift brass. Thanks.
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Old April 6, 2012, 12:24 PM   #34
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and they had little interest in what happened in from of the rim or belt, the case body filled the chamber and sealed the hot high pressure metal cutting gas, after the first firing? A different set of rules, I am sure the ‘leaver policy’ existed back then, I am the fan of the ‘leaver policy, once the case is blown out and fills/fits the chamber ‘leaver out’.

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Old April 6, 2012, 12:27 PM   #35
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???
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Old April 6, 2012, 12:45 PM   #36
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Wyoredman,

The Swift shoulder position has a tolerance of +0.010" in the chamber, but the rim tolerance is a bigger +0.015". A minimum thickness rim has 0.013" extra space ahead of it in a minimum depth rim recess, while a minimum length case shoulder has only 0.003" of extra room in a minimum shoulder length chamber. So it appears the shoulder is meant to be dominant and the semi-rim is just for more extractor claw grab.

The cartridge and chamber drawings are here.
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Old April 6, 2012, 01:01 PM   #37
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Hey, Thanks. And thanks for the Drawing link. Printed and straight into my Sierra manual.
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Old April 6, 2012, 06:00 PM   #38
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I think that I've learned from almost every post in this thread. I really appreciate everyone's help- from the guys with technical knowledge and the guys with the tech know-how, but layin' it out straight for what to do and the guys who are just a few steps ahead of me. But I'm especially thankful to unclenick for the excellent write-up on headspace.

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Old April 8, 2012, 11:53 PM   #39
Major Dave (retired)
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Speaking of gages...

how is the Wilson cartridge case gage used to measure headspace?

Actually, the manufacturers instructions on how to use it is quite clear - but what does it mean when my once fired 270 WSM brass heads protrude .020" above the surface of the high step on the gage?

I never have that problem with my 7X57 Mauser brass, or my .243 Win brass.
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Old April 9, 2012, 12:03 AM   #40
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Means your chamber is bigger than the gauge Dave.

Those drop in gauges don't mean much unless you want to be sure that you are setting the die up to ensure function in every gun ever chambered for that cartridge.
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Old April 9, 2012, 12:40 AM   #41
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Sometimes I think Mr. Guffy is off his meds, but he is very correct about looking for a bolt to fit your "special" chamber. I replaced bolts in hundreds of M-14's and thousands of M-16's. As he said, good luck finding enough variation to change anything.
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Old April 10, 2012, 09:11 AM   #42
F. Guffey
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Major Dad (retired), The L.E. Wilson case gage is a precision gage according to me, other reloaders refer to the gage as a drop in gage, there has to be a difference in perception skill/knowledge/technique between other reloaders and myself, I am not much on sitting/standing around with my hands in my pockets, when it comes to the Wilson case gage I understand when the case is ‘dropped’ onto the gage the case sits on the shoulder/datum of the gage, I know the top of the gage is ground to + ‘0’ – meaning below the top of the gage is shorter than minimum length, flush/flat with the top of the gage is .000” or minimum length and above the gage means the case is longer than minimum length from the shoulder/datum of the case to the head of the case.

I understand the correlation between minimum length and go-gage length for the case and chamber.

Back to everyone else, I perceive the Wilson case gage as an opened end gage, meaning it is up to me to determine the below-at-or above the gage with a height gage, or a dial caliper or (my favorite) the feeler gage, I use a straight edge across the flat of the gage (or case head) then with a feeler gage I determine the difference in height above the gage with a feeler gage. Wilson suggest a steel pocket rule, problem with the instruction? NO!, the problem is finding a reloader with a straight edge or a steel pocket rule, and there is the feeler gage, the transfer, the standard, the verifier, I am not beyond using the humblest of tools, I am not so conceited as to think I am too good, when I use the Wilson case gage and I find the case head is above the top of the gage I want to know by ‘how much’, same for below the top of the gage, again, I measure before and after, I determine the length of the chamber first, then form.

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Last edited by F. Guffey; April 10, 2012 at 09:15 AM. Reason: change set to sit
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Old April 10, 2012, 10:14 AM   #43
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The Rifleman's Journal has a detailed article on headspace:
Quote:
Setting the headspace on a resized case is important to ensure reliable functioning of the rifle, avoid damage to the rifle, maximize case life and achieve consistent accuracy. The objective of this article is to show you a method of setting up a full length resizing die that allows you to quickly adjust its setting to achieve the desired amount of shoulder set-back (headspace) for a number of rifles chambered for the same cartridge or for different lots of brass.

"Headspace" in the context of the rifle chambered for a rimless cartridge is actually the distance from the bolt face to the point in the chamber that is halfway up the shoulder. In the reloading context we often use the term to indicate how much clearance have we built into the brass case as compared to that distance. Simply stated, if the headspace measurement on a resized piece of brass is 0.002" less than the chamber headspace of the rifle in which it was fired, we often say the brass has 0.002" headspace. That's not a technically correct use of the term, but it will do for most reloading purposes.

More at link - http://riflemansjournal.blogspot.com...headspace.html
Related article "Short headspace on new brass" - http://riflemansjournal.blogspot.com...new-brass.html
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Old April 11, 2012, 06:15 AM   #44
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Unclenick referred to SAAMI's glossary regarding headspace; here's what SAAMI says:
Quote:
HEAD CLEARANCE... The distance between the head of a fully seated cartridge or shell and the face of the breech bolt when the action is in the closed position. Commonly confused with headspace.
Quote:
HEADSPACE... The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats.
Since the 1960's, some 'smiths have made gages that measure bottleneck cases' head-to-shoulder dimension so one can see how far a fired case shoulder gets set back when a full length sizing die is used on it. Later on, commercial versions made by RCBS, Stoney Point and others were available. These all had means to measure easily in thousandths of an inch.

Wilson's step-gage (and others using the same methods) required the human eye to judge the case head to reference dimension by comparing the case head's alignment with the two gaging surfaces.

But these all gave birth to the term "case headspace" which, while is not often understood by everyone, which is helpful to those who do understand it.

Note that a new case fired in a chamber does not have outside dimensions equal to the chamber dimensions. Depending on cartridge brass properties and peak pressure attained, there'll be one to a few thousandths inch difference in both case diameters and head-to-shoulder reference comared to the chamber's dimensions.

Unclenick mentions:
Quote:
If you do fireform a case and measure it, you then can compare it to sized cases to see how much wiggle room there will be for them in the chamber. As explained above, you don't want too much for best precision (smallest group size) and best case life.
Good advice. I think this pertains to bottleneck case head to shoulder dimensions compared to that of the chamber and not the case and chamber diameters. Close fit of case diameters to chamber diameters is not necessary for best accuracy. Especially when the clearance is so small the normal out-of-round characteristics of both case and chamber cause interference and that's not good for accuracy.
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Old April 11, 2012, 11:08 AM   #45
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“Wilson's step-gage (and others using the same methods) required the human eye to judge the case head to reference dimension by comparing the case head's alignment with the two gaging surfaces”

Bart B, those that are challenged and not familiar with tools and have trouble following instructions agree with you, I would suggest you locate a L.E. Wilson case gage and a dial caliper or a 2”-3” micrometer, with the dial caliper and or outside micrometer measure the length of the Wilson case gage. the 30/06 gage is 2.494 long, the 30/06 case maximum length is 2.494.

The instruction furnished by Wilson says to use a steel pocket rule, I say use a straight edge or a set up table, I say with a steel rule or a straight edge or a set up table the reloader that is familiar with tools can use a feeler gage to determine the length of the case from the shoulder/datum to the flat surface of the steel pocket rule, straight edge or set up table of they can keep up with an index of .000” thousandths.

Larry Wills uses Wilsons name and picture of a Wilson case gage on his site, I do not think Larry is fair to the Wilson case gage when he compares his tool to the Wilson case gage, I understand Larry and his motive, he is trying to sell his tool, you on the other hand must have another motive, it is not difficult for me to perceive the Wilson case gage as an open-end tool, it is natural for me to furnish the tools necessary to turn it into a precision tool, again, I make tools.

I have to ask, are you trying to reinvent head space? There were smiths and reloaders doing this stuff long before you, give them a little credit, I could quote information from a book printed in the late 40s, the smith/writer/author said there were different methods used when chambering a barrel, he said he preferred the store bought gages, but he said, other smiths have used other methods very successful, then there are those of us that have instructions that came with barrels, starts out with “If you have a head space gage etc., etc., if not use this method...”

I could furnish the name of the book and smith that wrote the book but indifference on this forum would cause someone to say “I never heard of him” and, I claim I never read Hatcher, having never read Hatcher allows me to disagree with those that claim/Hatcher “said”, when I disagree with Hatcher and someone believes I read the same book they go straight to “You can’s read” .

After all he moved the shoulder forward .080” thousandths, fired 30/06 cases in his new creation without case head separation, and I fired 8mm57 ammo in an 8mm/06 chamber, that is .127” thousandths head space without separation. Then a friend build a wildcat using an 03 action, 5 of the first 10 cases he fired suffered case head separation?????? Hatcher’s experiment failed, and my friends attempt at forming cases was successful, same action.

Nothing like being fair, nothing like being objective, “(and others using the same methods)” there is nothing wrong with having limited knowledge and skill when using tools. I believe it is common for the light to go out when the bolt closes and it gets dark, again, I check head space at least three different ways, 2 of those ways/methods do not include a head space gage, even though I have the tools necessary to make them and the means for checking them, head space gages are coveted, those that have them limit their use because of a limited knowledge and understanding of the tool.

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Old April 11, 2012, 05:25 PM   #46
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Guffey exclaims:
Quote:
Bart B, those that are challenged and not familiar with tools and have trouble following instructions agree with you, I would suggest you locate a L.E. Wilson case gage and a dial caliper or a 2”-3” micrometer, with the dial caliper and or outside micrometer measure the length of the Wilson case gage. the 30/06 gage is 2.494 long, the 30/06 case maximum length is 2.494.
Those that are not challenged and very familiar with tools and have no trouble following instructions will also agree with me.

And that dimension is not .30-06 chamber headspace; nor is it case headspace or headspace gage head to shoulder datum length.
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Old April 11, 2012, 07:03 PM   #47
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In the beginning when head space was discussed on the Internet the information provided always started “Well you see there is this datum line up there and that is what they use”, that was the limit of understanding, I said the datum in not a line, it is a circle, round hole, the round hole diameter hole for the 30/06, 280, 270, 25/06 is .375” ( 3/8” ) and they argued the datum was half way between the neck and shoulder juncture.

Back to the Wilson case gage. the datum, round in the 30/06 case gage is .375” in diameter, when the case is placed in the gage and the shoulder of the case rest on the datum the case length can be measured with a height gage, straight edge with a feeler gage, of a dial caliper. The datum in the Wilson gage has a radius.

And you said:

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“Wilson's step-gage (and others using the same methods) required the human eye to judge the case head to reference dimension by comparing the case head's alignment with the two gaging surfaces”



and I said that is not being fair to Wilson and the gage, I am not involved in a popularity contest, if you do not understand the Wilson gage join others, one claimed he was using the Wilson case gage as a chamber gage, he has not said a civil word to since, that was 2 years ago.

The Wilson gage measures two ways, from the datum to the mouth of the case and from the datum to the head of the case, again, I have a chamber with .016” thousandths head space, when using a tool like the Wilson case gage I add .014 thousandths to the length of the case from the shoulder to the head of the case and when measuring the length of the case I add the .014 thousandths, and I am the one that uses “other methods” those that are challenged can make wild guestimates with the eye, that is a choice.


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Old April 11, 2012, 10:51 PM   #48
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Guffey says he has a .30-06 a chamber with .016” thousandths head space. There's no way a .30-06 case will fit in a chamber with .016" between its bolt face and shoulder reference. Those cases are about 2 inches long where they need to fit in that chamber. I don't think one could compress a .30-06 case to fit in about 1/6th of an inch length just under a half inch in diameter. But then Guffey's an amazing person and he may well have a reloading press and die to size a case to fit that ultra-short chamber. But there wouldn't be any room for the primer and powder to fit in it.
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Old April 12, 2012, 09:14 AM   #49
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Yes Bart B., there is .016 thousands difference between the length of the chamber and length of the case from the head of the case to it’s shoulder, again, I measure first then form, then fire. There are those like me that do it then there are those like you that talk it to death.

Cases for the long chamber are not available, for those that do it, like me, not a problem, the 280 Remington case has a case length from the head of the case to the shoulder that is .051 thousandths longer than the 30/06, for those that do it, like me, forming/sizing cases for the long chamber is a matter of being able to adjust the press, die and shell holder to size and know where to form the new shoulder, This stuff does not lock me up, when forming 280 Remington to 30/06 by adding case length between the head of the case and shoulder I adjust the sizer die off the shell holder .014 thousandths, and then trim. No amount of talking will move the shoulder forward, others fire form, no skill necessary, chamber a round, pull the trigger, and wala, instant gratification, the person pulling the trigger became a fire former.

The length of the case in the perfect world is referred to as minimum length, I suggest measuring before firing, the Epstein/sweat hogs of the reloading world say “I am so confused” “I see no advantage to measuring first before firing” (typing slower), The Wilson case gage is a precision gage that is capable of measuring case length from the head of the case to the shoulder/datum in thousands, without checking the length of minimum length cases the reloader/owner with a Wilson case gage has no way of verifying the integrity of the gage or the ammo they just purchases or loaded.

As to minimum length and being able to keep up with two thought at once: Full length sizing? How does the reloader know when the press, die and shell holder is adjusted to full length size? How does the reloader know when the press, die and shell holder fails to restore the case to minimum length? I will repeat myself, I start by checking the gage .000, again, a case that is full length sized to minimum length is .000 in the Wilson case gage. In a go-gage length chamber the case is –.005 meaning the case is shorter than the chamber, back to the M1917 with .016 thousands head space and correlating gages, the minimum length/full length sized case is .005 thousandths shorter than a go-gage and in the perfect world represents .005 thousandths head space in the perfect chamber, the no go-gage is .009 thousandths longer than the minimum length/full length sized case or .004 longer than the go-gage. Then that leaves the field reject gage, the field reject gage is .014 thousands longer than the factory, new, over the counter minimum length/full length sized case, or .009 thousandths longer than a go-gage.

I form first then fire, I am a fan of cutting down on all that case travel, and I save one trip to the range. And, time is a factor, meaning I have neck sizer dies, I do not use them unless I am forming cases for a chamber I do not have dies for.

F. Guffey

Ands I said I check head space 3 different ways, if I found head space gages helpful I would make them, others believe precision gages come from Mars, meaning they believe mere mortals are not capable of making reliable gages, I believe there are those that talk about it and there are those that do it.

This reminds me of Jimmy Dean and his wisdom, when explaining the reason the chicken crossed the road, he said it was necessary, he said the chicken crossed the road to show the opossum it could be done.

I have a press, the press is adjustable. I have chambers, the chambers are not adjustable, I have feeler gages, I have straight edge tools, I can not adjust the chamber to fit my cases, so I do the logical thing, I adjust my press, die and shell holder to size cases that fit my chambers, no amount of talking can do that, for me? Not a problem, all I have to understand is .000, transfers, standards and a working knowledge of verifying.



F. Guffey
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Old April 12, 2012, 10:16 AM   #50
Bart B.
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Join Date: February 15, 2009
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F. Guffey submits:
Quote:
Yes Bart B., there is .016 thousands difference between the length of the chamber and length of the case from the head of the case to it’s shoulder..............
That's not headspace in the firearms industry and related participants' standards. That's "head clearance." If you choose to use it for your world, that's fine by me. But you're confusing countless numbers of others by doing so outside of your world. It's clear to me and others that you don't care. So be it.

If I were a judge in competition for such subjects as this one, for your last post I'd hold up a card with a "2" on it. Most others discussion points would get, at worst, a "9" from me.
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