Abstract: A telescopic drilling method includes the steps of drilling an outer bore through a surface, inserting a hollow outer conduit into the outer bore, and at least partially inserting a first hollow inner conduit through the outer conduit. Next, the method includes the steps of preventing the first inner conduit from moving longitudinal with respect to the outer conduit engaging a rotatable inner drill bit with a ring drill bit and further drilling the outer bore using a unitary drill bit head to a successive depth. The inner drill bit is disengaged from the ring drill bit and a second end of a successive hollow inner conduit is attached to a first end of a preceding one, and the preceding inner conduit is unclamped.