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Old February 6, 2013, 10:40 AM   #17
F. Guffey
Senior Member
Join Date: July 18, 2008
Posts: 5,491
Dan Newberry, as you are aware there is chamber length and case length (from the head of the case to the shoulder/datum). The .004” above the gage should be the effect the chamber had on the case when the case was fired, ‘not a problem?’ The .004” reading above the Wilson case gage is just right in there for nice to know if the rleoader did not measure the length of the case before pulling the trigger, meaning he does not know if the case head was dead on and level with the gage, below or above, back to “nice to know”,

I determine the length of the chamber before firing, when I measure the length of a case from shoulder/datum to the head of the case, after firing there are no surprises, do I have a Wilson case gage for every chamber I load for? No, once a reloader understands datums the reloader can purchase datums, make datums and collect datums.

Barrel stubs? I took a few to the last gun show at Market Hall in Dallas, I also took 10 +/- barrels, no one recognized the stubs as gages complete with case head protrusion.

“I don't think .004" is out of spec, if I'm understanding you correctly. I believe the no-go gauge won't chamber until you get to .006" over SAMMI spec. And that's just the no-go... the field gauge is going to give you a bit more than that, so I believe your chamber is fine”

In the perfect world his minimum length cases would have been perfectly? lever with the top of the gage, the .004” above the gage after firing (after neck sizing) would indicate the effect the chamber had on the case when fired. Sizing the case back to minimum length/full length size would be a matter of shortening the case from the shoulder of the case to the head of the case .004”, most reloaders would choose to bump the shoulder back .004”, When I try that part of the case body becomes part of the shoulder and part of the shoulder becomes part of the neck and when I bump the shoulder back without case body support the case body increases in diameter.


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.

F. Guffey
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