I see it all the time, the answer to stopping mass shooters is a "good guy with a gun", but who is that proverbial good guy with a gun? For the media and people unfamiliar with firearms, any old gun owner is a good guy with a gun. They see firearm ownership continuing to rise, and yet shootings still happen where no good guy appears. To the uninitiated, a guy with a few duck-hunting shotguns and a deer rifle in his safe is a "good guy with a gun".
It stands to reason that for your average person to stop an active shooter they need to be carrying a gun at the onset of the incident. There is probably not time to retrieve a gun from a vehicle and certainly not from a safe at home. That narrows our options down to people who conceal carry, which is already a much smaller percentage of overall gun owners.
Of those who conceal carry, how many carry consistently? How many people who conceal carry train to a level where they have the competence and confidence to intervene in an active shooter scenario?
Carrying a gun with the intention of being able to protect yourself and your loved ones is drastically different from making the conscious decision to actively put yourself at risk to help complete strangers. The skill level required to confront an active shooter is far higher than just defending yourself in your home or on the street. You are likely facing an armed individual who may outgun you and may be wearing body armor. You need to consider the presence of innocent people, responding law enforcement or other concealed carry holders, and the overall complexity of the situation.
An active shooter scenario will bear little resemblance to the hour or so of static shooting required of you in a typical CCW class. Most CCW classes involve shooting a bullseye-type target under no stress and usually no time constraints. No worry about being accountable for your shots, and no mental load required. This is also how most people train when they go to the range. There is nothing wrong with that if it helps you achieve the skill level for your personal goal when it comes to firearms. The problem is conflating the ability to hit a static target at the range or out in the woods with the ability to actively hunt down an armed target doing harm upon others.
There is certainly nothing wrong with knowing your limitations or understanding that your number one priority is you and your loved ones. As a first responder, my decision had already been made but now that I no longer wear a badge and have a baby on the way that calculation may change. Everyone has different circumstances and making the decision to intervene in a potentially lethal situation may look very different when you are alone versus out with your spouse and children.
At the end of the day a "good guy with a gun" is a man or woman who carries consistently, trains to a high level of competency, and has made the conscious decision to put their own lives at risk for the sake of others. I think this is an admirable goal for those who conceal carry and the whole driving force behind my upcoming Active Shooter Response class. Turning more responsible citizens into armed first responders is a practicable and immediate solution requiring no new laws, no constitutional amendments, and no government intervention.