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Rifles, Reloading, Optics, Equipment
Reloading
25-06 case head seperation?
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<blockquote data-quote="Bart B" data-source="post: 367082" data-attributes="member: 5302"><p>Rich, you're about right for your 5 thousandths extra headspace number.</p><p></p><p>SAAMI specs for .25-06 chamber headspace is from 2.0487" GO to 2.0587" NO-GO. (Note: the .25-06 headspaces on a .3750" diameter datum about mid point on its shoulder; same place the .30-06 does. The old 1.9480" GO headspace that many older gages are marked with is referenced at the shoulder-body junction diameter of .4410"). Specs for new cartridges' headspace is from 2.0519" to 2.0526". Which means when both ammo and barrel's chambers are within SAAMI specs, there'll be from -.0039" to +.0068" headspace clearance between the case head and bolt face when the round fires. Yes, it's possible to have the bolt bind on a round with maximum headspace in a minimum headspace chamber, but this rarely happens. New cases will easily withstand their back half stretching 7 thousandths the first time they're fired. And fired case headspace will be about 1 thousandth shorter than chamber headspace. </p><p></p><p>If the fired case is full sized such that its shoulder's set back too far, one's gone past SAAMI safety stuff. Do the math and see how there's only about 5 to 6 thousandths working space to set a fired .25-06 case's shoulder back Hence, the value of a good case headspace gage.</p></blockquote><p></p>
[QUOTE="Bart B, post: 367082, member: 5302"] Rich, you're about right for your 5 thousandths extra headspace number. SAAMI specs for .25-06 chamber headspace is from 2.0487" GO to 2.0587" NO-GO. (Note: the .25-06 headspaces on a .3750" diameter datum about mid point on its shoulder; same place the .30-06 does. The old 1.9480" GO headspace that many older gages are marked with is referenced at the shoulder-body junction diameter of .4410"). Specs for new cartridges' headspace is from 2.0519" to 2.0526". Which means when both ammo and barrel's chambers are within SAAMI specs, there'll be from -.0039" to +.0068" headspace clearance between the case head and bolt face when the round fires. Yes, it's possible to have the bolt bind on a round with maximum headspace in a minimum headspace chamber, but this rarely happens. New cases will easily withstand their back half stretching 7 thousandths the first time they're fired. And fired case headspace will be about 1 thousandth shorter than chamber headspace. If the fired case is full sized such that its shoulder's set back too far, one's gone past SAAMI safety stuff. Do the math and see how there's only about 5 to 6 thousandths working space to set a fired .25-06 case's shoulder back Hence, the value of a good case headspace gage. [/QUOTE]
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25-06 case head seperation?
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