In the late Eighties, along with the purchase by Tompkins, PLC, Smith & Wesson got a serious upgrade in tooling as the new owners brought the company into ISO 9000 compliance. Along with the CNC machinery came lasers for marking, supplanting old-school rollmarking for most purposes.
Looked at in a 100% crop from the EOS 5DS & 100mm f/2.8L macro lens, the burned aluminum looks pretty neat-o.