To know if a ban is effective, let's try a ban and buyback of semi-automatic weapons used in school shootings. If shootings go down, we will know if it is effective. Or, we can look at data from other countries with weapons bans, if the weapons they banned coincide with a decrease in, say, mass shootings then the ban was effective. We can then use that data as part of our ban data. It is simpler to start with a ban, then if we need people in schools to be able to conceal and carry because the ban only stemmed the tide by say 60%, we can.
Yes, on felons in jail. Unfortunately in school shooting scenarios, the shooters are first encountered with a weapon at the shooting. Yes, enforce all gun laws. We can certainly keep people who are mentally ill away from guns but we got a lot of people out there who have no access to mental health care to get that determination until it is too late.
I would like to see the gun control laws enacted, data collected and then start on giving people more weapons. Just my perspective.