A pneumatic actuator for use in pneumatic impact tools of the type used to engrave jewelry, and an impact tool adapted for the pneumatic actuator. The actuator includes a cylinder body with a pneumatic chamber housing a piston assembly reciprocating in response to pulses of pressurized air. The piston assembly includes a piston base and a striker pin in the pneumatic chamber, an outer end of the striker pin extending through and residing outside a forward end of the chamber. The outer end of the striker pin has an enlarged striker head of greater mass than the striker pin and/or the piston base in the chamber. A pneumatic impact tool is also disclosed, and includes a forward stylus section having a guide bore for the striker head and holding a graver assembly in spaced relationship to the striker head.