Abstract: A cylinder lock designed to prevent unauthorized manipulation of the lock using impact-driven methods such as a bump key. The cylinder lock has a plurality of first pin assemblies and at least one second pin assembly, containing a key pin, driver pin, and an elastomer plug, that is adapted so as to alter the linear displacement thereof through the use of the elastomer plug. When an impact-driven blow of a given intensity is applied so as to linearly displace the key and driver pins, the elastomer plug effectively absorbs the energy of the impact and fails to compress sufficiently to allow the key pin to clear the shear line, thus preventing the unauthorized manipulation of the lock.