I can't do it today, but at one time I was able to keep most of my shots in about 6" at 100 standing, one hand. Most target shooters can do that well if they want to win any matches; it is just that they rarely try because they don't shoot over 50 yards.
Off a rest, I could usually keep them in 3" with a Highway Patrolman. The best 100 yard 5-shot group with a revolver I ever saw was 1 1/2 inches, but I didn't shoot it; it was done by a friend off a rest, with a Model 27 8 3/8" barrel with a scope.
But at a year under the big eight-aught, I don't do that well any more. Age does catch up with us all.