Suppressor Alignment Gage

Geissele Suppressor Alignment Gauge

The Geissele Suppressor Alignment Gage (SAG) is a precision measuring device used to check the alignment of a suppressor with the bore of a firearm barrel. It is important to understand that the length of the suppressor is typically much longer than the length of the barrel/muzzle device/suppressor interface geometry. A small deviation at the mounting interface results in a much larger deviation at the silencer’s exit port. Deviations from the nominal value can also be cumulative, which exacerbates the silencer’s misalignment.

The Geissele SAG is made of hardened steel that has been ground to 0.002" below the nominal bore diameter. The outer diameter of the SAG is precision-machined and straight to within 0.001" along its entire length. Geissele hardens the SAG so that it does not wear down when exposed to abrasive powder residues, does not create burrs when sliding against misaligned baffles, and does not allow abrasive particles to penetrate the surface of the measuring device.

There can be significant variation in bore diameters and bore straightness. It has been found that an SAG size that is 0.002" below the nominal diameter works best for most barrels. The long length of the SAG aligns the gauge with the bore; it is not necessary to have a very tight-fitting gauge with the long length of the Geissele SAG.