WHAT DOES SMITH & WESSON MODEL 65 MEAN?

My Sig Sauer 516 dressed and in good shape with magnifier drop/flip scope and Eotech purple dot. Fires clean and correct anytime and I have yet to practical experience any or just one failure.The serial quantity is often stamped on the bottom in the grip frame. Many models (although not all) possess the serial quantity stamped to the body inside th