Stats compiled and analyzed by people smarter than us have rather conclusively proven that the accuracy of any gun/ammo combination is reliably measured starting at 20 shots, preferably 24 to 30.
Why do you think that the NRA has used 5 consecutive 5-round groups for decades?
There is even a statistical rule of thumb on 3-round groups are on average X smaller than 5-round groups, etc. Just looked at it last week, and pretty much ANY 1-inch group at 3 or 5 shots will probably never be more than 2 inches if fired in 10- or 20-round groups. Just multiply up to your reference group size.
In a rather modern 9mm semiauto a week or two ago, the less expensive Hornady bullets groups 1/3 the size of the more expensive Sierra bullets at 50 yards.
It all depends on how you measure "quality". Many of the cops at the North Hollywood shootout had handguns capable of 50-yard head shots, but the combination of lack of training/familiarity at that distance, and the pressures of trying to carefully aim without attracting fire, as I understand it led to very few attempted head shots at distance, despite the criminals casually moving about at a leisurely pace most of the time.