Thread: Headspace
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Old December 29, 2018, 12:24 PM   #12
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Join Date: November 13, 2006
Posts: 6,175
I was surprised.Searching "Headspace" was useless.Try "headspace defined"

The argument always comes down to this.The "headspace" of a firearm is established during manufacture. Its about using headspace gauges to represent and control the dimension from the breech face to the feature in the chamber the cartridge stops against. "headspace" is totally about the firearm itself,it is established and measured independently from ammunition.

You can pull any firearm off any rack and check headspace using only headspace gauges.

OP,I agree with you that functionally what we are often concerned with,especially when reloading,is "head clearance",as defined above in the excellent and useful post #11

A condition of excess or insufficient "head clearance" may exist in any firearm that is absolutely perfect in "headspace".

"Headspace" is about the gun. "Head Clearance " is about the ammo.,or more correctly,the fit of the ammo to the chamber.We can have an out of spec chamber and custom handload ammunition to ideal "head clearance"

To further confuse the issue,we can buy "Bushing type cartridge headspace gauges",that we can use to check that,regardless of the firearm,our handloads have been made to SAAMI "headspace" ? lengths....but I have commited a sin because I applied the term "headspace" to ammunition. IMO,there is the criteria of having a SAAMI spec firearm.
There is the criteria of handloading ammunition that meets SAAMI specs,that should work with SAAMI tolerances and work fine in any SAAMI spec chamber. I'm a heathen in that I commit the crime of referring to that concept as "Cartridge headspace" (In fairness,the cartridge does not have "space" It occupies space.)
Then there is "head clearance"which is what we might be functionally concerned with,to minimize case stretch and extend brass life. (Unless we are loading ammo to fit several rifles,or commercially reloading.)

We have two further issues to deal with.One is language,terminology,semantics,etc. The term "Cartridge headspace" is regarded by many as intolerable,because it is technically incorrect.

IMO,its useful in the explaination of the concepts .I'm wrong.

The other issue is what happens when we try to discuss this topic. The search of "headspace defined " will perhaps shed light.We get into the swamp,the weeds,folks who use the extractor as a headspace datum feature,etc,etc,etc,etc.

Last edited by HiBC; December 29, 2018 at 12:36 PM.
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