The present application describes a an image-guided, vacuum assisted, percutaneous, coring, breast biopsy instrument which may be conveniently mounted to an x-ray machine, and incorporate into it a firing fork that is easy to remove and includes a means of maintaining the firing fork perpendicular to the base when the biopsy probe is fired into the patient. It would further be advantageous to design an image-guided, vacuum assisted, percutaneous, coring, breast biopsy instrument which may be conveniently mounted to an x-ray machine which would incorporate a firing fork with a means to maintain the firing fork perpendicular to the base when the biopsy probe is fired into the patient that is easy to remove without the use of special tools.