An apparatus for drilling out a plug of material, the apparatus comprising: a base plate having a top surface, a bottom surface, and a central longitudinal axis; a circumferentially-extending side wall extending distally from the top surface of the base plate, the circumferentially-extending side wall terminating in a circular distal end surface; a drill bit centered on the central longitudinal axis of the base plate and extending distally therefrom, the drill bit comprising a distal portion, a proximal portion and an intermediate portion extending between the distal portion and the proximal portion; wherein the intermediate portion of the drill bit comprises a first laterally-extending flat comprising a cutting edge disposed a first distance away from the central longitudinal axis towards the circumferentially-extending side wall and a second laterally-extending flat extending a second distance away from the central longitudinal axis towards the circumferentially-extending side wall, and further wherein the first distance is greater than the second distance.