Gun drill bushing inserts (GDI) are used with gun drill liner (GDL) bushings in holemaking applications with El Dorado, DeHoff, and Lahr gun-drilling machines. The inserts install into the liner bushings to form two-piece bushings. A range of inserts can be used with one liner bushing, which means machine operators only need to change the inserts to change the ID of the drill bushings when the drill size changes or when worn inserts need to be replaced. These drill bushings install into fixtures to guide, position, and support drill bits during holemaking tasks. The bushings keep the drills from wandering or bending as they enter the workpiece. They also maximize chip clearance and minimize the risk of the drills marring the workpiece.