People committing murders in Detroit, Chicago, LA. are not acquiring firearms under the laws and policies of gun control. Because they are criminals. What do you propose is done otherwise? Ban firearms completely? Rifles too? What about the 300 million existing firearms? Are responsible gun owners suppose to hand over their guns to the government under your proposal? Do you believe that the people committing murders you mentioned above would comply with such a request? If not to what lengths should the government go to ensure your gun ban is seen through, do they enter and search the homes of every citizen? If so to what extent may they search?

It's simple to spout out emotional reactions but the simple fact is it's a contentious and nuanced topic so think through the implementation. Using basic logical deduction to draw your own conclusion may even allow alternative solutions to emerge. Perhaps murder is not committed because of guns but because the perpetrators are in poor mental health, impoverished, lack education and so on. Maybe if we improve those conditions it will solve your goal- which is less mass killing and murder.

Point here is don't make a single solution your goal to a problem, make solving a problem your goal and think through. If you don't feel passionately enough to do that than concede to those who are.