When you imagine a gunfight, what do you think of? Nothing about this brief battle plays out according to the idea of a typical gunfight.
Look at the shooting positions. Have you practiced shooting from a position like this? Look at how quickly the attackers approach and start shooting. Are you ready to respond instantly? One clerk moves to the left and is trapped in an exposed corner. The other moves to the right and finds cover but does not have his gun. In order to return fire, he needs to leave his cover to retrieve his gun. Then he decides to shoot through the concealment barrier in front of him, which drives off the first attacker.
The second robber is so intent on finding cash he seems to ignore the gunshots until he realizes rounds are coming at him. At that point, he makes a hasty retreat without even stopping to tell the clerk shooting at him that the substandard caliber the clerk has chosen is inadequate for self-defense.
What About Caliber?
Looking at all of the elements of this gunfight, where would you say caliber falls on the level of importance? Look at the speed and violence of action shown by the attackers. Look at the close range and nontypical shooting positions. Look at the available cover and concealment. Caliber, in this incident, is inconsequential. Are you ready for this type of fight? What would you do to make it home alive from this store?