GUN DRILL MACHINING CENTER APPLICATION DEEP HOLE DRILLING ON CONVENTIONAL MACHINE TOOLS L=1,5xD 1. Operation - Pilot hole Workpiece D +.0010”+.0004” Coolant circle 2. Operation - Deep hole drilling D High pressure Filter pump Gun Drills in Machining Centers Centering / guiding hole for gun drill operations on machining centers. Bushing guide barrel for gun drill stabilizing in machining center. 706