It all depends on your definition of "rapid fire". For me, that term means shooting not only fast, but accurately.
About 2 rounds per second (full to empty is 3 seconds) is about the best I can do with any accuracy at 15 yards using factory SD ammo. I might shave it down some with 148gr target wadcutters.
For me, there's a "cadence" I reach when shooting. The gun goes *bang*, recoils and as I lower the gun I'm already cocking for the next shot and as soon as I'm on-target with the front sight I can squeeze just a tad further to make another *bang*.
The S&W revolver's action allows you to "feel" the point at which the cylinder locks up and from there it's a short squeeze to manufacturing once-fired brass. On a B27 silhoutte target, my lock-up occurs about the time the sights are lowering past the target's head. At this point you can pause and aim a bit more or continue with moving down and time your shot just as your sights hit COM.
Just remember: Speed is fine. Accuracy is final! --Bill Jordan
BillCA in CA (Unfortunately)