The field of the invention generally relates to probes, related devices and methods for measuring material properties. In an embodiment, the present invention provides a test probe for use in a reference point indentation device. The test probe has an end proximal to a tip and an end distal to the tip. The distal end of the test probe has a self-centering mate comprising a countersink of about 90 degrees to about 100 degrees to a depth of between 0.010 in. and 0.035 in.