In reality in nearly every case where a policeman wanted to use a real gun in the past they still use a real gun.

Do you have a source for that?

One method would be to look at the number of police killings and see if it changed the trend. But it's pretty tough to get the number of American police killings, let alone the estimate a trend and determine causes.

One could imagine a policy decision to arm people with tasers instead of guns, which is not subject to your complaint. People are rarely disarmed, but new locations could make different choices about how to arm security guards. But I do not know the proportion of guards armed in various ways, let alone the trends.