Brownells Fillister 8-40 Sight Screw Counterbore

The Brownells Fillister 8-40 Sight Screw Counterbore is a precision gunsmithing tool designed to cut counterbores for fillister-head sight screws using the 8-40 thread standard. It allows gunsmiths to properly seat sight screws flush or recessed into firearm receivers and sight bases, ensuring a clean, professional fit. Ideal for dovetail sight installation and other sight-mounting work requiring exact screw seating.