A method is presented for making a penetration test of a homogeneous ceramic material which includes driving a cylindrical hardened steel probe pin of a predetermined configuration into the material to be tested. At the beginning of the test, the pin is snugly assembled in an enclosing tubular cylinder with a flattened end of the pin in registration with one end of the cylinder. After the pin is driven into the material to be tested by use of a closely controlled powder charge in a suitable gun, while holding the tubular cylinder, one may accurately measure the penetration where the flat end of the pin has penetrated the surrounding cylindrical tube. The novel probe pin assembly includes the probe pin assembled in an embracing tube member.