Abstract: A piston actuated drilling tool includes a housing, a top sub, a piston and a drive sub. The piston has a nose at its forward end that is slidably mounted for reciprocating movement within the housing and which strikes a mandrel located at the forward end of the housing. An integrated retaining and bushing system has a retaining ring arranged for preventing the mandrel from detaching from the rest of the tool. The retaining ring encases a bushing for co-operation with the piston nose to stabilise and guide the piston and provide a timing event for percussion of the tool.