A biopsy needle assembly (100) includes a mandrel (102) within a cannula (200), the needle assembly is fired into a target tissue to obtain a tissue sample using a force source imparting movement to the needle assembly. The mandrel and cannula design, and force source characteristics minimize needle deflection, and allow the needle assembly to excise extended length tissue samples. The mandrel forms tissue retention ridges (140) within a tissue sample region to reduce fragmentation of the tissue sample.
