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Co-Ax® Case and Cartridge Inspector

Improve your shooting accuracy by fine-tuning the uniformity of your cases and cartridges.
  • Bullet Diagram at Forster ProductsMeasures “accuracy-critical” dimensions:
    • Neck wall thickness
    • Case 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″
  • Inspects overall case lengths up to 3.50″
  • Quality manufactured from precision-engineered automotive-type castings
  • Uses the same Pilots as our Case Trimmers, sold separately

Case Neck Wall Thickness

A case neck with irregular thickness can add inconsistent tension to the bullet and ruin your precision. Unfortunately, even newly produced brass can vary in thickness from one lot to another.

A variation of at least .0015″ indicates the need to resize and outside turn the case neck.


Case and Cartridge Runout (Concentricity)

The outside of the cartridge is ideally aligned in a concentric circle around the axis. Using the wrong shell holder or improperly indexing can alter the “concentricity” of a case. Concentricity is used to identify
a number of issues that affect ammunition loaded for accuracy.

Variations of .0015″ and greater in the case’s neck, shoulder and body indicate correction by fire forming to your rifle chamber, resizing or outside neck turning to ensure the most consistent performance. Upgrading to our Bench Rest® Seater Dies may also improve concentricity.


Bullet Runout (TIR)

The angle and position at which the bullet enters the bore, commonly known as total indicated (bullet) runout, or TIR, is ideally zero. Most shooters limit their TIR to no more than .002” to .005”, depending on where you measure along the cartridge. “Tipped” bullets – with high TIR – are certain to shoot off target.

Variations of at least .004″ generally also call for correction by fire forming to your rifle chamber, resizing or outside neck turning to ensure the most consistent performance. Upgrading to Bench Rest Seater Dies may also lower TIR.

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