The SureFire Bore Rods manufactured by Geissele Automatics are intended for concentricity check prior to firing suppressed on a new platform. This video explains how to use them and why.
The rod most closely represents the bullet flight path and will show any issue of alignment, if present. Recommended to verify barrel to adapter to suppressor alignment, for any new build or any previously unshot setup. Choose the corresponding rod for your caliber rifle or carbine.
For more information, visit http://www.surefire.com/sf-bore-alignment-rod.html
