First insert the gage into your caliper or a height gage, at this point set your caliper or dial indicator to read 0.
Next insert a .47-70 case into the gage. Measure again and read the actual thickness of your rim.
Optionally if you have a case, you consider as your optimum standard, put that case into our gage. Next set the caliper or dial indicator to 0. Hereafter every case measured will read + or – from this 0 setting.
If you want to find out what your rifles headspace is take a very small piece of pure lead, at least .080” thick. Insert it into the rim area of the chamber of your rifle and close the action on it. You may have to close the action several times to compress the lead into the rim areas. You can now use this as your optimum rim thickness or possibly .001 to .002 less than the lead sample measures. Now I suggest you find a case with this run thickness or possibly .0005 to .001 less and save this for your standard in the future.
If you have any questions, call us, 479-629-5566, 9am to 9pm central time Mon-Sat. If the line is busy leave a message we will call back. Thanks very much for considering our firm for your needs.
Tom Wilson Fort Smith, AR 10-7-23©