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Old February 14, 2013, 11:50 AM   #24
F. Guffey
Senior Member
 
Join Date: July 18, 2008
Posts: 2,527
I think you're getting length and headspace terms mixed up.




http://www.saami.org/PubResources/CC...Winchester.pdf

1.630 chamber from the datum to bolt face MINIMUM! MAXIMUM, add .010” The case length from the datum/shoulder 1.634 minus .007. Maximum Cartridge/Minimum Chamber, again, I determine the length of the chamber from the datum/shoulder to the bolt face, because I am a reloader with dies and presses with threads I off set the length of the chamber with the length of the case from the shoulder back to the head of the case.

And notice SAAMI does not designate case length as having head space, I guess it is optional”

Bart B. I know you can read, I have no ideal what your motive is for ignoring information. That leaves me to wonder if you are that desperate for attention.

“Chamber "headspace" (as well as case headspace) is what the ammo industry and reloaders refer to as the head-to-datum length;” I included a link from SAAMI, nothing about head space and the case, only length.

It is not the industry that has the problem, it is the reloader, memory work is nice as in “Repeat after me, Head space is etc., etc..” After repeating “Head space is etc., etc..” a reloader can not size a case to off set the length of the chamber from the usual places as in from the head of the case to the shoulder and from the bolt face to the shoulder of the chamber.

Without the ammo industry and SAAMI information I determine the length of the chamber from the bolt face to the shoulder of the chamber, I use the direct route, my route skips the ‘talking about it’, my method/technique is about doing it.

After you have already declared the case has head space you have no choice but to insist it does. I do not preach head space, I do not insist a reloader understand datum is ‘measured from’, a boring conversation in the real world starts with “Head space is...etc..” In the real world I have never found anyone explaining ‘head space’ that knew what they were talking about. Getting a reloader to measure the length of the case from the shoulder/datum back to the head of the case is as difficult to get them to understand a minimum case length from the shoulder to the head of the case and full length sizing is returning the case to minimum length. Point? The new factory case has a length that can be measured from the shoulder of the case to the head of the case.

You preach full length sizing as being the only way to go, I disagree, there has been a number of manufactures take liberties with “repeat after me etc..” They built gages designed for measuring the length of the case from the datum/shoulder to the head of the case, then! declared their tools were head space gages, one, when asked about his self declared head space gage many times got to the point he could not ignore the critic, he said ‘I know, but I am not the only one, so, I named it a head space gage” ( or something to that effect ), then he continued to call his comparator a head space gage. Even then it should have been understood by the ‘GO TO GUYS’ on forums to make it understood the case length gages were not head space gages, but, it seemed there was more to gain by agreeing with the manufacturer, desperate for attention?

I was approached, it was suggested that the reloading industry would benefit if I agreed with a manufacturer, it was suggested we work together. I up set a few, about that time I made it very clear I did not p$#p products that were only nice but not necessary and mislabeled. I did suggest to anyone that purchased a comparator thinking it was a head space gage and later decided they wanted their money back do so with the understanding they were mislead.

Bart B. you started by declaring the case had a head space, gages that measure case length from the shoulder to the head of the case are case length gages, some are comparators used to measure case length, I make case length gages, again, I collect datums, I make datums and I purchase datums.

In the big inning forums were eat up with a drawing of a case and or chamber, no one knew what it was about but there was an arrow pointing to a line with the line labeled datum line, that was the total amount of information know to a reloader, when finished discussing the topic, the discussion ended with “and that is how they do it”.

F. Guffey
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