inwardly toward central region 52 of base 42 fig1 this effectively reduces the outer diameter of rock head 40 so that it is able to fit within bore 32 of pipe 24 auger 22 is withdrawn from pipe 24 and as rock head 40 exits pipe 24 drill bits 60 pivot about retaining pins 80 and rock head returns to its second position the hex connectors 48 50 are then detached from one another and rock head 40 may then be replaced with dirt head 26 the springs 82 utilized in this device are manufactured to be strong enough to be compressed and expanded numerous times so that rock head 40 can be reused springs 82 are also sufficiently strong enough to withstand the rigors of boring through the rock it will be understood by those skilled in the art that rock heads in accordance with the present invention are sized to be used in conjunction with pipes of a defined range of internal diameters within that range of pipe diameters the drill bits will pivot to a greater or lesser degree in order to be received within the bore of any one particular pipe the drill bits do need to pivot to a degree sufficient to allow for forward or rearward motion of the rock head and auger through the pipe if the fit is too tight so that travel through the pipe would be substantially hindered then.