My 4 5/8 shoots about 1/4" left @ 7 yards . That's the best it gets and it takes Remington RN Lead .38SPL's to get there, Magnums are about3/8" off the mark.
Now a lot can be corrected by widening the rear notch in the opposite direction that you want the bullet to fly. Mine needs some file work soon as I buy a good set.
I absolutelly love the .357 Vaquero!