The GR String Shot Backoff is an explosive device that creates a depth-specific shock wave to assist in unthreading a downhole tubular connection and thus retrieval of pipe, stuck packers or fishing tools (for example, an overshot). It can also be used to remove corrosion from pipe, open perforations and jump collars, and to remove jet nozzles in drill bits to increase circulation. It will not damage the pipe string and can be run through restrictions as narrow as 0.75 in. The String Shot Backoff can also be run in the annulus to back off pipe from the outside, positioned at depth using a casing collar locator or CCL/gamma ray tool combination.