to create microfractures within hard rock 12 to increase the penetrating effectiveness of drill bit 28 explosive projectile 40 is defined to include any matter which can be accelerated through gun barrel 34 to contact hard rock 12 and to increase the penetration of shot hole 22 through hard rock 12 in a preferred embodiment of the invention as shown in fig2 explosive projectile 40 includes a secondary explosive 50 encapsulated within case 52 which detonates under pressure or impact this embodiment is useful because secondary explosives are relatively safe to transport and to handle and can be moved into magazine 42 with minimal risk of premature detonation secondary explosive 50 within explosive projectile 40 detonates upon contact with hard rock 12 to generate a shock wave for pulverizing fracturing or otherwise disturbing hard rock 12 fig2 illustrates secondary explosive 50 as being completely encapsulated within case 52 however secondary explosive 50 can be formed on one end of case 52 in other embodiments the material forming case 52 can be selected to accomplish different objectives in one embodiment case 52 can be formed with ceramics which fracture into small fragments and are easily removed from shot hole 22 case 52 can comprise metallic organic or chemical materials and compounds and can be selected depending on cost mass.