Personal defense does not usually mean killing people a kilometer away, it means a nearby threat.
I am sure you can kill a nearby person just as effectively with a rifle as you can with a handgun.
The only thing that handguns do is that they are easier to carry and to conceal. That is IMHO not necessarily a good thing.
Your store owner my just as well use a shotgun (which is even more effective at short range). He can keep it behind the counter, as most shop owners in the US do with their guns (I dont think many are carrying them under their coat).
Unless you are a person that really is in danger every day (policemen, bank employees, or store employees that carry large sums to the night deposit, maybe also taxi drivers), a handgun is not needed to defend yourself (you would have to be really unlucky to get into such a situation). This is why in Austria, only these people get to carry handguns legally. They also have to go through a mental evaluation and they must not have a criminal record. In addition to this, there is a waiting time of a few weeks before you can actually pick up the gun at the store, after you bought it (cool down time to avoid amock runners getting guns).
To me this makes perfect sense.
However, I have personally witnessed a modern revolver hitting a target 10 cm high and 2 cm wide at a distance of about 80 meters
The members of our anti terror unit do that with the glock handgun, on one hundred meters. They routinely practice shooting handguns at the same range meant for our soldiers to train with assoult rifles at...