Co-Ax® Case and Cartridge Inspector

Improve your shooting accuracy by fine-tuning the uniformity of your case and cartridges.2Co-Ax-Inspector_small

Case and Cartridge Inspector Instructions

Pilots for Case Trimmers and Case & Cartridge Inspector

Accurate performance from your ammunition is absolutely dependent on uniformity of both the bullet and the case. Achieving that uniformity is not possible without an accurate, reliable measuring device.

Forster’s exclusive Co-Ax® Case & Cartridge Inspector provides you with the ability to ensure uniformity by measuring three critical dimensions:

  • Measures “accuracy-critical” dimensions:
    • Neck wall thickness.
    • Case, bullet and cartridge runout (concentricity).
  • Uniquely supports case/cartridge to check both bullet and case alignment in relation to the centerline (long axis) of the case/cartridge.
  • Measurements are in increments of .001″.
  • Accommodates cartridges from 204 Ruger to 45-70.
  • Includes precision dial indicator, accurate to .001″.
  • Maximum overall case length that may be inspected is 3.50″.
  • Quality manufactured from precision-engineered automotive-type castings.
  • Uses the same Pilots as our Case Trimmers.

(Note: 17 cal. Pilot is not compatible with this tool.)

The Inspector is unique because it checks both the bullet and case alignment in relation to the centerline (axis) of the entire cartridge or case.


Case Neck Wall Thickness (pictured in Fig. 2)

Due to variations in case manufacturing and/or an uneven brass flow after repeated firings, uneven neck walls do occur. The Co-Ax® Case and Cartridge Inspector allows measurement of the neck wall thickness far more accurately than dial calipers which cannot properly measure round objects. By slipping the case onto the proper pilot (available from Forster) and taking measurements with the tip of the gauge at several points around the diameter of the case, the thickness of the case neck at all those points can be determined. A variation of .0015″ or greater indicates inconsistent case thickness and indicates the need to either re-size or outside-turn the neck of the cartridge.

Case Neck Runout (pictured in Fig. 2)

This concentricity check is set up by positioning the stop bar so that the V-bracket is supporting the neck of the case. Place the ball point of the indicator so it is touching the case about 1/8″ from the shoulder. Rotate the case. If variation of greater than .0015″ to .002″ is registered, you will want to look for ways to make the cases more consistent.

Bullet Runout of Loaded Rounds (3.5″ maximum cartridge length) (pictured in Fig. 1)

Bullets will not leave a rifle barrel at a uniform angle unless they are uniformly seated. The Forster Co-Ax® Case and Cartridge Inspector is unique in that it allows the measurement of both the bullet and case alignment in relation to the centerline (axis) of the cartridge. A runout of .000″ to .002″ is considered excellent; a runout of .004″ or greater suggests a problem that should be corrected to ensure the most consistent performance. Solutions could include either re-turning the outside neck of the cartridge or using a Forster Bench Rest® straight line seater die.

The Co-Ax® Case and Cartridge Inspector will handle from .20 caliber to .45-70 cartridges. The Inspector is quality manufactured from precision engineered automotive type castings. It comes complete with a precision dial indicator which is accurate to .001″ and has a travel of 1/2″. The Co-Ax® Case & Cartridge Inspector functions best with Forster pilots manufactured since 1996. Maximum overall cartridge length that may be inspected in this tool is 3.50” inches.

For ordering proper case mouth pilots, please use our Caliber Search feature.

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