But, for now, I can't help feeling that most CCWs carry guns which aren't exactly crime intervention grade, not to put too fine a point on it.
To offer a slightly varied opinion, I don't think it is the guns that matter so much, or the caliber. Anybody landing shots on the bad guy in an active shooter situation is going to be improving the situation by degrading the shooter, keeping the shooter from being able to have free reign.
The problem isn't the guns but people's understanding of how to proceed in such a situation. Most folks, if mentally prepared at all, are prepared for the stereotypical situation of some form of robbery, not a lot of people around, home invasion or dark parking lot. They aren't mentally prepared and almost certainly have not trained for a situation where they find themselves in the middle of active carnage occurring within the space of a fairly concentrated group of people.
One of the guys at the AZ shooting had gone to ground and and only was able to determine who the shooter was once the shooting stopped and the shooter was the only one upright who wasn't running away. In other words, there was several seconds of extreme chaos and while folks knew there was shooting and great danger existed, they didn't necessarily have a clear view of just who the shooter was.
Even if a person at the shooting had a gun and was able to draw it before getting shot by Loughner, determining the corrrect point to shoot may have been overwhelming. Having an unobstructed shot at the shooter is just one criterion for making the shot successfully, assuming you have a clear shot. If folks are running into you while trying to get away, then your shot isn't going to be clear or it won't be reliably steady. Then you need people to not be directly behind or just to either side of the shooter and to not be running into your shot trajectory as they flee in panic.
It would be sad to have the means to stop the shooter and not be able to stop the shooter for some reason. It would be horrific to shoot the wrong person in trying to keep from being sad.
Being in such a situation means being in a highly chaotic and quickly changing situation where every delay in trying to respond is another bit of time the shoot can and in this case continued to do harm while at the same time an incorrect response may result in your own injury or you shooting the wrong person. Once the shooting starts, everything changes for most pepole. Everyone who moments before were just regular people in a crowd are now all potential victims and all potential bad guys. Not only must you identify the shooter, but also identify others who may also be bad guy shooters and distinguish them from other good guys such as yourself. Some people do very well in these situations naturally. Most do not. Some train to be able to do well in them. Most do not. Of those that train to do well in such situations, not all become good at it.