A bioabsorbable sealant plug that expands in response to contact with moisture in a mammalian body is optimally positioned in a biopsy tract to seal the biopsy tract when a biopsy procedure is completed. In a first method, the leading end of the sealant plug is advanced through the lumen of a coaxial needle by a plunger until a leading end of a supporting leg abuts the patient's skin surface. A second method is performed with a pistol-shaped tool having a trigger that enables adjustment of the plunger. A third embodiment includes a plunger having a bifurcated end that grasps the plug. A fourth embodiment has a turning nut that causes compression of a gasket that clamps down on the plug. A supporting rod and coaxial needle are in parallel relation to one another in a fifth embodiment.