A single piece expansion plug and method of using the same in connection with a tool is provided. The plug has an inner recess extending partially into a top of the plug, the inner recess defining a tapered inner wall. The plug is installed with a tool having a tapered end at a greater angle with respect to the taper inner wall. The tool presses against the tapered inner wall to expand the plug against a hole. The tool includes a pin that retracts against a spring to seat the plug in the hole to be sealed such that the pin contacts the plug prior to the tapered inner wall and tapered end coming into contact.