Wilson Case Gauge
This is a top quality case gauge that is designed to
help you measure the exact length "headspace" of your cases. This measurement is made from the shoulder to the base
of your case. It allows you to compare your fired cases to the size of your particular chamber.
I always use a case gauge when reloading any rifle caliber because it is important to "know" that your headspace is being set correctly.
This gauge allows you to take both go and no-go measurements of your cases. If you push the shoulder
too far back during resizing, it creates an excessive headspace condition. This stretches your cases and it will shorten their life
considerably. This can also cause case head separations and put enormous pressure on the face of your bolt. On the
other hand, if the shoulder of your resized case is not getting pushed back at all, your handloads will usually fail to chamber after a few firings.
Notice that this particular case gauge shown is adjustable. This particular case gauge is made for a belted magnum
cartridge. Factory belted ammo is designed to headspace on the belt. However, when reloading it is far better to headspace
on the shoulder and it is important to always bump the shoulder of your cases back at least .001" - .002" to
ensure a reliable fit in your chamber. There is no accuracy gained by crushing a cartridge into your chamber. This will
only deform your case and affect concentric alignment.
Factory rifle chambers are all made within SAAMI dimensions. However, the tolerances are nowhere near as
close as a custom chamber due to the required volume of production work. Remember, it's important to keep in mind that this type of
case gauge does not check the width of your handloads. The case width problem that commonly affects belted magnums will
not be detected by this gauge. If your handloads are too tight in your chamber and they measure fine with this gauge, be sure to
measure the width of your case at the pressure ring . . . . with calipers.
