Your modern S&W revolver may be safely carried with all of its chambers loaded.
Do not try to put it on "half-cock," because it doesn't have that feature.
Do not carry it fully cocked. That is unsafe.
Carry it with its hammer down on one of its loaded chambers. There is an interposing safety device that keeps its hammer from contacting its firing pin until its trigger is pulled to the rear.
I suggest against using the so-called "safety lock" that is built into this pistol. Certainly, never carry it locked, anyway.
The safety lock will keep the pistol from being fired, but it will not keep it from being handled by someone who doesn't know what he (or she) is doing. Thus, someone who is ignorant of the safe-gun-handling rules may pick up the pistol believing that it is locked (from prior casual experience handling it) at a time when it is not locked, and might cause a deadly accident.
Better than any so-called "safety lock" is your personal control over your gun(s). Before anyone is allowed to handle a gun, explain the safety rules, and then, with watchful vigilance, rigorously enforce them.
Don't depend upon mechanical safety devices. Depend only upon the safety device built into your head, right between your ears.