A machine for modifying a sidewall defining a die cavity formed in a die with a slug retention groove comprising: a base grounding the machine to the die adjacent the die cavity ; a slide arrangement carried by the base , the slide arrangement having a fixed slide block attached to ground and a movable slide block movably coupled to the fixed slide block for movement relative to the fixed slide block and the die cavity in a direction toward or away from the die cavity ; and a machining head carried by the movable slide block for movement therewith relative to the fixed slide block and the die cavity in a direction toward or away from the die cavity , the machining head having a slug retention groove forming tool used to form the slug retention groove in the cavity-defining sidewall ; a machining head motion limiter formed by abutment between a stop arm of the movable slide block and a stop landing of the fixed slide block that limits movement of the movable slide block , machining head , and tool relative to the fixed slide block and the die cavity in a direction toward the die cavity defining a maximum range of travel of the movable slide block , machining head , and tool ; and characterized by a removable stop comprised of a plate having an abutment positioned between the stop landing of the fixed slide block and the stop arm of the movable slide block , against which the stop arm of the movable slide block abuts during travel of the movable slide block , machining head , and tool in a direction toward the die cavity to limit movement of the movable slide block , machining head , and tool relative to the fixed slide block and the die cavity toward the die cavity to a range of travel less than the maximum range of travel without the removable stop installed and in that the plate is position-adjustably attached to ground for enabling position adjustment of the stop relative to the stop arm and die cavity . a base grounding the machine to the die adjacent the die cavity ; a slide arrangement carried by the base , the slide arrangement having a fixed slide block attached to ground and a movable slide block movably coupled to the fixed slide block for movement relative to the fixed slide block and the die cavity in a direction toward or away from the die cavity ; and a machining head carried by the movable slide block for movement therewith relative to the fixed slide block and the die cavity in a direction toward or away from the die cavity , the machining head having a slug retention groove forming tool used to form the slug retention groove in the cavity-defining sidewall ; a machining head motion limiter formed by abutment between a stop arm of the movable slide block and a stop landing of the fixed slide block that limits movement of the movable slide block , machining head , and tool relative to the fixed slide block and the die cavity in a direction toward the die cavity defining a maximum range of travel of the movable slide block , machining head , and tool ; and characterized by a removable stop comprised of a plate having an abutment positioned between the stop landing of the fixed slide block and the stop arm of the movable slide block , against which the stop arm of the movable slide block abuts during travel of the movable slide block , machining head , and tool in a direction toward the die cavity to limit movement of the movable slide block , machining head , and tool relative to the fixed slide block and the die cavity toward the die cavity to a range of travel less than the maximum range of travel without the removable stop installed and in that the plate is position-adjustably attached to ground for enabling position adjustment of the stop relative to the stop arm and die cavity . <EOS>