The information I gave was correct as to how the standards are set up to work. If you have a personal standard that says a used gun with mismatched bolt has to have headspace as good as that of a newly chambered rifle, that's your personal choice. It's just not how the standards are set up.
As far as SKS safety, or that of any other self-loader with a floating firing pin goes, it seems to me extra headspace makes more room for the case to move the primer away from the firing pin and less likely it would meet resistance to chambering as the bolt closed. So, if anything, it would reduce rather than increase slamfire likelihood. If you are worried about how a couple of thousandths will affect pressure ring stretch in the case, then you resize for the chamber. For disposable brass in new ammo it should be no concern at all. Look at Hatcher's description of an experiment with a chamber moved 50 thousandths forward on purpose. It had no case failure issues (though I sure wouldn't try to reload a case stretched that far). So I don't see how safety would be adversely impacted by having a chamber that meets the standard requirements.
My first Garand came from the DCM with a chamber 0.007" over minimum, which is 0.001" over Clymer's NO-G0 for .30-06 of 0.006" over minimum (some companies make 0.005" over as NO-G0) and 0.003" under FIELD. After bedding, the first group out of it from prone position put 10 rounds into 0.7" CTC. With the sizing die set up to push shoulder's back two to three thousandths it did just fine on brass life, too, and lasted another 2,000 rounds before it was shot out. Nary a problem. You just have to load for the gun.
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