A method and assembly for preventing unauthorized manipulation of common cylinder locks, as executed by use of the principles of the Bumpkey or Blowgun methods. The pin assembly, containing a tumbler pin and a driver pin, is adapted so as to alter linear displacement thereof, by forming a recession in one of the pins contained in the pin assembly, and an engagement means, in the other of the pins, for engaging the recession, such that when an impact-driven blow of a given intensity is applied so as to linearly displace the tumbler and driver pins, the pin engagement means engages the pin recession, strongly binding the tumbler and driver pins together, thereby, blocking the shear line and, consequently, preventing unauthorized manipulation of the common cylinder lock.