Smokey Face

Have you noticed all the incidences of violence on airlines? How many were stopped by Air Marshals who are supposed to be on flights? I have not heard of even one.

While your idea has some merits, it will be generally be perceived as a bluff.

The way to stop mass shooting is to stop massive reporting about them. It stimulates copy cats. Instead, mass publicize the conviction and sentencing of mass shooters. The perception of ACTUAL punishment is a better deterrent.

In my town, we have plain clothes CUSTOMERS, and clerks, and everybody knows it.
Don't even need a sign, and no appreciable hold ups in over 9 years.

Put the signs over the ones that call the place a GUN FREE ZONE

I wish Biden would just declare the US a Cancer Free Zone, and empty the hospitals.