Jeff: One other item in this is that group sizes are measured from center to center, not the distance from the outer edge of a bullet hole across to the farthest outer edge. It's just another convention which began Lord knows how many decades ago.
Another generalization is that a "one-minute" rifle reliably averages such a group (sometimes the jerk behind the trigger jerks the trigger), and the "standard" group is five shots.
Forty or fifty years ago, one MOA was regarded as really great in a hunting rifle. Today's precision machining makes it halfway commonplace.