Yeah, lots of variables in answering that question. With a 6 1/2" .357 Blackhawk: raising the gun to straight out from the shoulder, at arm's length and firing within 1 or 2 seconds, NOT using the sights, I can keep my shots inside of 12" at about 30 feet.
Doing the same thing, firing a little faster (under 1 second), I can consistently hit an standard paper plate at 20 feet.
Using the sights and a bench rest, etc. is of course a whole different story. Bullets, loads, barrel length, and other things can wipe accuracy all over the place. I think with my regular handloads (16.6 gr. H110, 158 gr. XTPs @ >1500fps), I can probably do 3 inches at 50 yards.