A reaming or coring bit with an articulated steel pilot protruding about 36 in (91 cm) beyond the face of the bit. The diameter of the pilot is slightly smaller than the set inside diameter of the bit; its upper end is a piston fitted tightly inside a single-tube barrel with its attached coring bit. When lowered into a borehole in which a deflection wedge has been set, the pilot section forces the coring bit to ream out the first part of the deflected hole at a point about 20 in (51 cm) above the tip of the wedge. Reaming is continued to about 6 in (15 cm) below the wedge tip, at which point the pilot shoulder reamer is withdrawn and replaced by a bullnose or deflection bit.