Back in the 1970's or so the rule of thumb with the model 19 (at least where I come from) was that .38 Specials were to be the regular diet & .357 was for duty use. Excessive use of .357 loads were thought to "loosen up" the gun prematurely. Apparently this was not true. I think that if anything got "loosened up" it would have been the shooter's hand.