I just acquired a S&W .455 Mark II, serial number 35284.
The LHS of the barrel:
SMITH & WESSON .455.
Note the full stop. Nothing on the RHS of the barrel.
It has been refinished so some of the markings are smeared looking. It has the Broad Arrow, etc., on the LHS upper rear of the frame. Other than the re-blue and replacement M1917 stocks, it is unmodified.
Haven't lettered it and probably won't, but from the data Jim has compiled, it looks like it probably shipped at the very end of 1915.