A gundrill and a method of forming deep holes using such a gundrill having an elongate tubular shank 242 and a cutting tip 244 with a novel profile is disclosed. The cutting tip 244 and tubular shank 242 are both provided with a tubular central region supplying pressurized drilling fluid and a non-circular fluid cross-section which defines a drilling fluid return path in conjunction with the bore of the hole being formed. The cutting tip cooperates with the bottom of the hole being formed such that the cutting tip 244 and the bottom of the hole form an outlet. The outlet size is carefully controlled in order to maintain relatively high drilling fluid pressure in the bottom end space and the flow of drilling fluid discharged from the end space is controlled to cool the cutting surfaces and to effectively remove chips as they formed. <IMAGE>
