I'm new to this forum and hopefully this will not be my only find that I have questions about as I am far from an expect. While roll searching I came across this quarter that has a dimple on. After doing some research I think this may be a rockwell test mark ... any opinion.
I don't think so. It is my understanding,a rockwell test mark would only appear as a dome on only one side of the coin. Yours looks like a dimple on one side and a dome on the other. To me it looks like your quarter was used as target practice.
I've used a Rockwell gauge many many times while running the tempering ovens at TCA and if done properly it should only leave the tiniest of marks where the diamond tip makes contact. However, most people not knowing how to properly use the machine often "over tighten" leaving a much bigger mark (and getting an incorrect hardness reading). This however is not from a Rockwell as the shape is wrong (usualy square tip) and size is too large. My thoughts is someone probably hit it with a center punch.
