It' doesn't really matter. The twist rate has only one mission in life, to stabilize the bullet. To often you will come across people that think the twist rate can do some magic stuff. The importance of the twist rate can NOT be transfered directly from a bench rest rifle to a revolver.
Anything from 1:10 to 1:20 will stabilize a 148 grain HBWC out to 50 yards. And will do so inside a speed range from as low as you never will go, and upwards way beyond stupid.

The magic here is just what JKeefer is guiding you towards, a good quality barrel. Kreiger, Shilen, Douglas, Lothar Walther all good stuff.
I'm using a 1:17,7 polygon barrel from Lothar Walther.