It isn't a magic number so don't get hung up on it. A 4" group at 25 yards is a heart sized group and is bad enough to make any boogerman give up his quest for your life and your property. It's also good enough to stop the neighbors mad dog from having your leg for his lunch.
A 1" group has its disadvantages too. I fired a few and actually lost points at the S.E regional championships in Shreveport Louisiana because the scorer and the referees couldn't see evidence of 10 shots and that was with my 45. Fortunately I never fired many groups that size so my shots were easy to count on paper. I have seen people like Harmon, and Pasquarella do it fairly regularly, no tricked out guns, just good guns, lots of sweat equity and careful attention to basics. I figure if I am doing 3" I am doing my job and if its 6" I'm still on target and still doing my job.
Best way to weed out the tall tales from the shooters is to get them on range with you. Then be prepared to hear the excuses of why it wasn't happening at that point and time. An experienced shooter always has his excuses lined up and ready to go. You should hear some of mine.
