My go to talking points on this are:
You cannot eliminate violence by removing weapons. Weapons are not the source of violence, only a method. In every country where guns were severely regulated or removed, the violent attacks did not stop, the attackers merely changed weaponry. Now, a good counter argument to this is, that guns are an incredibly powerful weapon and therefore allow an attacker to do more damage than they would with a less powerful weapon (knife, bat, fists, etc). This is true. If you could wave a magic wand and remove every gun from the planet, then the violent offenders would do less damage as they would be forced to use a less powerful weapon. But you can't, and this brings me to my second point.
You cannot remove guns from the United States. People often point to Australia or the UK when it comes to successful removal of guns from the general populace. These places are unique in that they are islands. To get anything in or out of there without going through a checkpoint is far more difficult than it is to get something across the two massive land borders of the US. Granted, I would doubt much is smuggled into the US from Canada, but it is a point of undeniable fact that a buttload of drugs are smuggled into the US from Mexico on the regular. If you ban/highly regulate guns in the US, the law abiding citizens are going to turn them in, and not only will the criminals refuse to turn in those they already have, but they will be able to get more through the inevitable gun trade that will arise across the Mexican border. Want to have fun with your liberal friends? Agree with them about gun regulation and argue for stronger border enforcement in order to support those gun regulations.
There aren't as many "gun deaths" as people think there are. When people bring up numbers on gun deaths, they often find sources that lump in suicides, accidental deaths, and justified police shootings. (discharge a firearm in a school parking lot? Some statistics will actually call this a school shooting. Another fun one to look out for) The actual number of violent human-shooting-human gun deaths is high in some areas (areas with stricter gun control... coughcoughchicago), but overall, it's just not as big a problem as they make it out to be. Violent crime? Definitely an issue, but far more violent crime is committed without guns than with. And to take away a person's ability to defend themselves with a superior weapon could be called immoral. Hence...
Guns are force equalizers. Let's go back to the magical world where you can wave a wand and all guns vanish on the planet. Sally, who used to be a gun-owner to protect herself from men who are twice her size, no longer has that ability to defend herself. She bought a knife and keeps it on her hip, but one night Sally is cornered by a mugger/rapist/bad dude who has a knife of his own. He also has 100lbs on her and is far stronger. Do you think her knife is going to do much good? Sally is going to be forced to do whatever this fella tells her to do, and her rights are going to be infringed upon. Now, Sally might not have the superior strength/skill to fight off Mr Attacker with a knife, but she does have the strength to pull a trigger. By taking away guns, or making them less accessible, you are limiting Sally's ability to protect herself.
The long story short here is, if you ban guns (or regulate them to the point they might as well be banned), you are not stopping violent crime from occuring, you are only depowering law abiding citizens and empowering criminals.