If the bolt would close on the GO gauge or minimum head space and not close on the NO-GO gauge you are under maximum and over minimum. (Or in the ballpark)

The last new 100 .243 cases I purchased were anywhere from minus - .001 to .009 or shorter than minimum head space. Fired cases were plus + .002 over GO or minimum head space.

[img width=337 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP7241.jpg[/img]

As you can see there was maximum of .009 difference from the new cartridge cases and the go gauge, "WHY" would you use a new cartridge case of unknown length to check head space. Why would you use another rifle of unknown head space to judge the rifle you are working on. Also if you were just installing the barrel "where" did the fired brass come from???

A RCBS Precision Mic could be used to get much better readings of your cases using the GO gauge as reference "Zero".

Bottom line, you can't use a cartridge case to check head space if you do not know how long the case actually is.


Example below, this new unfired case is .006 "UNDER" minimum head space (GO) and should "NOT" be used to set your head space.



Simple ways to adjust for your rifles head space setting for anything over minimum or GO.

[img width=600 height=410]http://i122.photobucket.com/albums/o254/bigedp51/7-17-201054345PM.jpg[/img]

[img width=600 height=350]http://i122.photobucket.com/albums/o254/bigedp51/7-17-201054719PM.jpg[/img]