I believe that guns don't kill people. People kill people. I agree that second amendment rights should be protected, yet some types of firearms do seem excessive. But ultimately it isn't what type of weapon is available that is of concern to me. It's WHO has access to these weapons.
For example, people of all characteristics drive all sorts of vehicles. Some drive tiny electric cars, some drive your everyday sedans, while others drive giant SUVs. Then there are those who own flashy sports cars and those who command commercial 18-wheelers. And anyone who passes a driving test and has been deemed eligible to drive safely can purchase any said vehicle or at least get behind the wheel of such street-legal vehicles. What matters isn't what vehicle is being driven. You can toss me the keys to the fastest sports car and I will probably still drive like a paranoid new mom with her baby in the backseat (though sport cars don't even always have a backseat). But there are people who drive recklessly regardless of what car they drive. Those who drink before getting behind the wheel... those who speed or disobey traffic laws... those who have lost their ability to make sound judgments... those who have no regard for human life... so on so on.
Are some types of street legal super fast sports cars excessive? Sure. As may seem to be the case with the semiautomatic weapons...
But there are existing laws to keep formula 1 vehicles off the streets as there are regulations to keep some of the more military grade weapons/fully automatic weapons off the streets.
Guns aren't inherently bad. Yes, they can be dangerous. But so can the keys to your car if put in the hands of a young teenager looking for a joy ride, an elderly person with delayed responses or poor vision, or an intoxicated individual who thinks they are fine to drive.
The focus needs to be on better regulating and endorsing existing gun laws and also in tightening the regulations and strengthening the steps required for known and potential threats to purchase guns. Let's look at who is causing the violence and less at what their weapon on choice is.