21st Century Concentricity Gauge Base with Sliders x 3

Measures bullet runout, neck, body case mouth and inside neck concentricity

Accommodates cartridges up to .50bmg

Adjustable case stop

Wheel eliminates error, holds case on roller bearings ensuring accurate measurement

Deviations in concentricity of your cartridges will have an adverse affect on the accuracy of a round. If a case is non-concentric or the seated bullet is “tipped” over to one side, the bullet will not meet the rifling in a consistent manner. This misalignment of the bullet with the bore might be corrected during firing, but will likely cause pressure differences, stress and physical damage to the bullet prior to leaving the muzzle. Such misalignment may be caused by a non-concentric case head, body, shoulder, neck, or mouth. There are many steps in the reloading process that can cause these issues, and being able to measure concentricity is the first step in diagnosing and improving your reloading procedures.

The perfect concentricity gauge

Most concentricity gauges marketed for reloading use a height indicator to measure concentricity. Unfortunately, while more economical, this type of gauge was not designed to measure a rotating object. Inaccuracies are introduced as the long indicator rod flexes and bounces during use. We have therefore elected to use a horizontal dial test indicator in our products. This type of indicator has been the industry standard for measuring concentricity and run out for decades. These are the same indicators we use to set up and calibrate the CNC machines in our shop.

The Wheel assembly is a powerful tool that improves the accuracy of the gauge. A light touch on the top of the wheel is all that is required to rotate the case quickly and smoothly.

In addition to measuring outside case neck and body concentricity and bullet run out, the horizontal dial test indicator allows for measurement of the inside of the case mouth and neck. Our gauge is highly configurable and can be used to measure nearly every conceivable cartridge. The adjustable sliding bases accommodate loaded and unloaded cartridges of all sizes up to 50BMG.