As you prob.know guesstimating not the best approach to sighting in. Much depends on your load,velocity,bullet,etc.etc.
Winchester-Western standard flush-seated WC load at 753 feet per second from the archetypal target revolver- a post war K-38. This gives it an on-target velocity of 667 fps at fifty yards with a drop of 8" from the muzzle. It takes the bullet only .212 fractions of a second to proceed from the muzzle to the 50 -yard bull. In the real world, not many adverse consequences of the laws of physics occur to a bullet in two tenths of a single second regardless of its overall lack of ballistic goodness.
Hope this helps