Type 99 without Serial number

[Sentryduty]

The powers that be have a process that can detect the compressed, displaced, whatever, steel under the stamped numbers. I forget if it was X-ray or chemical or what.

My father was welder by trade, and said they had done marking recovery just like that during his courses. He said to remove all trace of a stamped serial or marking a person would have to go surprisingly deep into the metal. I will have to ask him what process they used. I recall it may have been a chemical, I wonder if it was magnaflux or some other option?