check to see if Model 18-3 is in time. accuracy and safety depends on cylinder being in correct position when hammer is dropped. cock hammer back into locked position. cylinder properly in time is locked up. cylinder stop is in center of picture slowly pull trigger, cylinder stop will first drop, then raise up about mid point between slots on cylinder. as hand rotates cylinder, stop will dovetail into slot locking up cylinder. if you can rotate cylinder with hammer fully cocked, then revolver is out of time. fixing requires ordering an oversized hand, requires custom fitting. use a feeler gauge to check gap between cylinder and barrel. call S&W for tolerances, which could be different for each model. Model 18-3 measures .007in front gap (.008 feeler gauge was a forced fit), .006in for rear gap. side to side rotation at lockup ended up at .003in after new stop was installed. Fin.... whew, what a long writeup!!! and yes double action is smoother and cylinder lockup is tighter.